Book Summary – Onyx – Lux Series – Book 2
- Jason Montero
- Dec 22, 2025
- 25 min read
Updated: Dec 22, 2025
Book summary by chapter of Onyx. Includes spoilers from the first fever to the end of the book. Kat becomes the core of an alien blaze that devours her identity, dragging her through impossible betrayals, onyx cages, and a covert war. From the first tremor to Dawson’s return, her world fractures between pain and longing, until a shared sacrifice with Daemon binds them in a promise that defies every rule.
Introduction – Onyx
There’s no turning back when the fire inside you no longer comes from a fever, but from a power you never asked for. Onyx, the second installment in the Lux Series by Jennifer L. Armentrout, turns the search for truth into an emotional battleground where every choice has a cost. Kat must face invisible enemies, betrayals wrapped in promises, and the terrifying possibility of losing what once made her human.
As her connection with Daemon deepens and the secrets of the Department of Defense become undeniable, the line between love and destruction begins to blur. In this book summary by chapter, we follow every rupture, revelation, and awakening power—from the first fever to the moment one betrayal changes everything.
But to understand how this silent war between humans, Luxen, and Arum began, you must first go back to where it all started. Reading order of Lux Series ➤
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Chapter Navigation
Chapter 1 Summary – Onyx – The Trace, the Fever, and the Lake
Chapter 5 Summary – Onyx – Blake, Jealousy, and an Ordinary Afternoon
Chapter 10 Summary – Onyx – A Birthday of Confessions and Memories
Chapter 15 Summary – Onyx – Defense Questions and Fear Sets In
Chapter 25 Summary – Onyx – Hidden Wounds and a Shared Refuge
Chapter 35 Summary – Onyx – Will’s Deal
Chapter 1 Summary – Onyx – The Trace, the Fever, and the Lake
Kat starts the day facing Daemon Black’s usual provocative game in class, a tension marked by desire, irritation, and the alien connection that emerged when he healed her. Although Daemon insists on eliminating the trace that makes her vulnerable to the Arum, Kat resists accepting a relationship based on that artificial bond. During the school day, Kat’s physical discomfort worsens, accompanied by dizziness and persistent pain, while Daemon’s proximity intensifies sensations she cannot control. After returning home, Daemon insists on taking her out for a run to reduce the trace, even though Kat is clearly sick. The fever rises alarmingly through the night and Kat, disoriented and consumed by unbearable heat, leaves the house and goes to the lake seeking relief. Daemon finds her just in time and rescues her from the icy water when she loses consciousness, beginning a crisis that will put her life in immediate danger.
Chapter 2 Summary – Onyx – The Hospital and the Obsidian
Kat wakes in a confused state after an extreme fever that consumes her for days, drifting in and out of consciousness while voices, cold hands, and bright lights surround her. Her body undergoes an intense process, with sensations of internal fire followed by cold that extinguishes the flames, just as someone removes her obsidian necklace. She remains hospitalized for four days, not clearly remembering how she got there or what happened during the worst part of her illness. As she regains strength, Kat is discharged and goes home with her mother, who is deeply worried about how close she came to losing her. Gradually, Kat discovers that it was Daemon who took her to the hospital in the middle of the night, a fact that awakens new doubts about the connection between them and how much he can feel through that bond. Although she feels physically better than ever, the lack of clear answers leaves Kat uneasy, aware that what happened was not a simple flu and that something has definitely changed within her.
Chapter 3 Summary – Onyx – The Vanished Trace and the Bet
Back at school, Kat is surprised to discover that her trace has completely disappeared, although the connection with Daemon remains intact. The revelation reassures and frustrates her at the same time, since she had hoped both phenomena would end together. During Biology, she meets Blake Saunders, a new human student whose arrival sparks general curiosity and Daemon’s silent discomfort. Later, Kat meets Daemon in the library, where he confirms that he rescued her from the lake and stayed with her during the most critical night of her fever. The closeness rekindles emotional and physical tension that both try to deny, leading to a kiss that unleashes an energy surge capable of damaging the surroundings. Still wounded by the past, Kat decides to set boundaries and rejects a romantic relationship despite her feelings. Daemon, confident in himself, proposes a bet: before the New Year, Kat will admit that she is in love with him, officially declaring the emotional war between them.
Chapter 4 Summary – Onyx – Objects That Move and Unsettling Signs
Kat spends the afternoon alone at home and begins to notice strange occurrences that she cannot logically explain. A glass breaks, the tea pitcher tips over, and objects seem to move without her touching them, which awakens fear and confusion. She tries to convince herself that everything has normal causes, although she knows she has already lived through too many coincidences. She seeks refuge at Dee’s house, where the atmosphere is chaotic and comforting at the same time. There she discovers a strange reaction on her arm, a red and irregular mark that doesn’t hurt but unsettles her. Upon returning home she finds Daemon, who accompanies her and shows a closer, more reflective side. They share an intimate conversation about Lux, the war, and loss, revealing deep wounds. Kat perceives a bond more intense than desire, something emotional that destabilizes her. That night she continues to feel changes in her body and surroundings, accepting that something within her is awakening and that she can no longer ignore it.
Chapter 5 Summary – Onyx – Blake, Jealousy, and an Ordinary Afternoon
Kat tries to regain normalcy at school while dealing with increasingly frequent phenomena that she cannot control. During lunch, the arrival of Blake Saunders sparks immediate interest, as he is human, friendly, and represents a life without alien secrets. Blake integrates easily and shows clear interest in Kat, which provokes a tense reaction in Daemon, who watches from a distance. Kat agrees to go out with Blake after class and enjoys a relaxed afternoon at the Smoke Hole café, where they talk about books, blogs, and hobbies without fear or supernatural tension. The experience is comfortable and pleasant, although lacking the intensity she feels with Daemon. Blake flatters her and shows genuine interest in her world, which reinforces her attraction. However, Kat cannot fully shake Daemon’s presence or the connection that binds them. The apparent normalcy becomes a deceptive respite, a prelude to an event that will completely change her perception of herself.
Chapter 6 Summary – Onyx – Awakened Power and the Truth
When a branch falls violently near Blake, Kat acts on instinct and stops the object in midair, revealing that she possesses abilities impossible for a human being. The effort leaves her exhausted and disoriented, confirming that something has changed within her. Daemon intervenes immediately, protects the situation, and takes her away before Blake can comprehend what happened. At home, Kat confesses that she has been moving objects without touching them for days and describes the intense pains that follow each episode. Daemon deduces that Kat is using Luxen abilities, something never seen in humans, possibly caused by the healing and the connection created during Baruck’s attack. He tries to communicate with her in his real form and confirms that they are still connected, even though the trace has disappeared. Daemon promises to investigate what is happening and protect her, while making it clear that the situation is dangerous. Kat understands that she is no longer the same and that she will have to face a transformation that threatens to put everyone at risk.
Chapter 7 Summary – Onyx – Power Out of Control and Uncomfortable Confessions
Kat arrives at class exhausted after a sleepless night and discovers that her emotions directly influence abilities she can no longer deny. The anger she feels toward Simon causes her book to fly out and hit him, confirming that she can move objects without touching them. Although she manages to hide it, Daemon notices what happened and is amused by the situation. Later, Blake shows genuine interest and agrees to come to the party, which leads Kat to invite him to her house first, defining the outing as a date. Meanwhile, Dee confesses the pressure the Luxen community faces to pair up and reproduce, revealing a rigid system that marginalizes those who fall in love with humans. Kat gains a better understanding of Daemon’s past and the weight he carries. Amid intimate conversations, family, and memories of her father, Kat reflects on true love and chooses to go ahead with the date, even though she knows her feelings are increasingly tangled and dangerously intense.
Chapter 8 Summary – Onyx – A Quick Date and Inevitable Jealousy
Kat prepares for the party in a dress from Dee and welcomes Blake at her house, who arrives with roses and sincere compliments. They share a close moment that leads to a proper but hollow kiss, leaving Kat with a sense of guilt and confusion. Together they go to the party, where Blake introduces himself as her partner and Daemon appears shortly after, provoking immediate tension. Kat perceives Daemon’s magnetic attraction and cannot ignore it, despite being with Blake. Ash’s presence alongside Daemon awakens intense jealousy that Kat does not want to admit, which drives her to flee the house overwhelmed by contradictory emotions. Unable to control what she feels, she walks away barefoot to an empty dwelling, convinced that what she is experiencing makes no sense. The night makes it clear that the normalcy she seeks with Blake cannot extinguish the deep, irrational, and increasingly painful connection that binds her to Daemon.
Chapter 9 Summary – Onyx – Shattered Windows and Forced Truths
In the darkness, Kat encounters Simon, visibly hurt and drunk, who threatens her to make Daemon back off. The situation spirals out of control when Kat’s emotions cause several windows to explode in a burst of glass, endangering them both. Simon flees in terror, and Kat is devastated as she realizes the true extent of her powers. Daemon appears and protects her, admitting without remorse that he punched Simon for slandering her. Although Kat disapproves of the violence, she’s grateful for his defense. Daemon reassures her that no one will believe Simon. On the way back, a heated argument erupts, filled with jealousy, accusations, and uncomfortable truths about Blake, Ash, and the kiss they both remember. Kat tries to deny her feelings, but her reactions betray her. Daemon declares he can’t forget what exists between them, making it clear that the connection is not just alien—it’s emotional, intense, and already impossible to ignore.
Chapter 10 Summary – Onyx – A Birthday of Confessions and Memories
Kat turns eighteen with a strange calm, gets back to blogging, receives a new laptop, and watches her mother happily share dinner with Will, which stirs both gratitude and inner conflict over her father’s absence. After a family meal and shared cake, Kat is left alone at home, cleaning, singing, and settling into a domestic routine that soothes her. Daemon shows up unannounced, brings laughter and embarrassment, and confesses he came to apologize for the previous night. Amid jokes, ice cream cake, and physical closeness, they clear up misunderstandings about Ash and acknowledge shared wounds. Daemon presents theories about their connection, investigates the origin of Kat’s powers, and warns of the danger they represent. The conversation shifts toward Luxen history, Skaros, and the Department of Defense. Between shared interests and confessions, the tension softens, and the night moves forward into a silence filled with meaning.
Chapter 11 Summary – Onyx – An Interrupted Date and Visible Jealousy
Kat begins the week convinced that nothing has changed after the night spent with Daemon, though her thoughts keep drifting back to him. In class, sock jokes rekindle their playful bond and draw curious looks, while Kat tries to focus on her date with Blake. During dinner, their conversation flows around new food, hobbies, and reflections about escaping reality. Blake shows sincere interest, but Daemon’s shadow returns when rumors surface about the fight with Simon. Kat avoids digging deeper and chooses not to ruin the evening. Peace is shattered when Daemon barges into the restaurant, invades their space, and triggers an awkward accident that ruins the date. Although Blake remains understanding, Kat leaves with Daemon after discovering there’s an urgent matter. The night makes it clear that Daemon’s jealousy runs deep and that normalcy is becoming increasingly unreachable.
Chapter 12 Summary – Onyx – Defense Watches and Loyalties Clash
Kat attends an unexpected meeting at the Blacks’ house, surrounded by Luxen tension over the increased presence of the Department of Defense. Matthew explains that a satellite was destroyed during the Halloween energy surge, raising suspicions and surveillance. Although the elders protect Daemon, it’s clear he will be closely watched. Tempers flare when Andrew blames Kat for the danger, prompting a violent reaction from Daemon that exposes his protective side. Kat intervenes and manages to stop the fight, proving her bond with him. After the group leaves, concern lingers, and Kat speaks with Daemon about the real threat posed by the DoD. He admits that some Luxen deemed threats were eliminated in the past. The revelation leaves Kat shaken, aware that the danger is no longer abstract and that Daemon could become a real target.
Chapter 13 Summary – Onyx – The Chair, the Kiss, and the Impossible Truth
Kat loses control of her emotions and releases an energy burst that sends a chair flying, injuring her knee. Daemon helps her, cleans the wound, and explains the existence of the Source, comparing her reactions to how young Luxen responded as children. Physical closeness heightens the attraction, leading to a kiss unlike the others—deep, tender, and full of desire. Kat moves the chair without touching it, confirming that her powers respond to emotional triggers. After the moment, an honest conversation unfolds in which Daemon admits that his feelings don’t come from the connection or jealousy over Blake, but from something real and long-standing. Kat remains doubtful, convinced it’s all a product of the alien bond and the challenge. Although Daemon promises not to give up and says he’s not ashamed of her, Kat pulls away, unable to trust and afraid to accept what she feels—aware that giving in could completely break her.
Chapter 14 Summary – Onyx – Flowers, Suspicions, and the Marked Clearing
Kat learns of Simon’s disappearance and receives a rose from Daemon in class, a public gesture confirming he won’t hide his interest. Police question students, and Kat senses that some officers aren’t human. Over several days, Daemon showers her with thoughtful gestures and spends time watching over her, while Blake fades into distant messages. Daemon invites Kat for a walk and takes her to the clearing where Baruck died—a place saturated with residual energy and scorched earth that will never heal. There, they talk about death, guilt, and the burden of taking a life. Daemon investigates whether the DoD has detected the energy at the site and remains protective as Kat’s recent disturbances increase. Romantic tension resurfaces, but Kat sets boundaries and rejects his kisses. On the way back, Daemon proposes a formal date and defends the authenticity of his feelings. The conversation is cut short when Department of Defense vehicles appear, blocking their way out.
Chapter 15 Summary – Onyx – Defense Questions and Fear Sets In
Agents from the Department of Defense intercept Kat and Daemon in the clearing. Daemon lies about why they are there and convinces Kat to go with the agents to avoid a confrontation. During the ride, Nancy Husher and Brian Vaughn interrogate Kat with calculated questions about Daemon, his family, and their closeness, making it clear they’re suspicious. Kat stays calm and hides the truth, though fear grows when her phone rings, exposing the lie. Back home, Dee and Adam try to comfort her, but Kat senses Nancy didn’t believe them. Hours later, Daemon returns safe and sound. Kat, relieved, hugs him impulsively, revealing without words how much he means to her. Daemon assures her the DoD doesn’t suspect anything serious and promises to protect her. Still, Kat feels something dark approaching and pulls away, convinced that everything they’ve experienced will bring dangerous consequences.
Chapter 16 Summary – Onyx – Thanksgiving Under Lights and Silences
Kat spends Thanksgiving alone while her mother works, avoiding the Luxen gathering out of nerves and fear of her uncontrolled powers, which that day cause accidents at home. Daemon shows up with prepared food, turns the dinner into an intimate moment, and uses his powers to create a warm atmosphere that stirs memories of her father. They share wine, laughter, and a connection that makes Kat question whether her feelings go beyond the bond. Later, they put up an improvised Christmas tree, a gesture that breaks Kat’s emotional defenses and makes her cry with gratitude. That night, Daemon stays over, and the closeness in bed deepens the attraction. They kiss slowly, without crossing any lines, and the shared silence reveals unspoken emotions. Kat falls asleep fully aware that something real is growing—and that she can no longer deny it without consequences.
Chapter 17 Summary – Onyx – The Frozen Diner and Blake’s Truth
Kat agrees to meet with Blake to clarify their relationship, though she feels guilty after the night spent with Daemon. During dinner at the Smoke Hole Diner, Blake displays an unsettling intuition by anticipating others’ actions. The situation shifts when Kat’s obsidian reacts and an Arum appears in the diner. Blake freezes everyone in place and reveals supernatural abilities as he confronts the Arum, destroying it with an obsidian weapon. Daemon bursts in, and tension erupts between them until Blake declares he knows what Kat and Daemon are. In the car, Blake confesses he is a mutated human, the result of having been healed by a Luxen in childhood, which led to his family being killed by agents. He explains that the Department of Defense is hunting humans like Kat, capable of developing unstable powers, and warns that she is in real danger if she doesn’t learn to control them.
Chapter 18 Summary – Onyx – Forced Alliances and a Silent Breakup
Blake expands on his story and explains that mutated humans can be even more powerful than Luxen, which is why the Department of Defense hunts them—to control or eliminate them. He describes how Kat developed abilities after being healed and warns that losing control could harm her or attract Defense and the Arum. Though Daemon remains distrustful, Kat realizes she needs help to protect her mother and friends, and agrees to train with Blake under Daemon’s supervision. Later, Kat returns home and confronts Daemon, who interprets her meeting with Blake as a betrayal driven by fear of facing real feelings. Their argument exposes jealousy, pride, and deep wounds. Kat insists it’s not her problem—words that wound Daemon more than expected. He leaves abruptly, leaving Kat devastated and aware that by denying her feelings, she may have lost him just as she was ready to accept them.
Chapter 19 Summary – Onyx – Courage Before Choosing
Kat spends the day crushed after the argument, comparing the pain to the loss of her father and accepting that her feelings for Daemon run deep. She tries to distract herself by writing and organizing books, but the emptiness persists until Daemon shows up. Their reunion is tense and an attempted apology is cut short by Blake’s arrival, reigniting jealousy and friction. Training begins with both present, and it’s clear Kat’s control is unstable. Blake explains possible mutation effects and suggests trying voluntary moves while Daemon watches with suspicion. Kat makes minimal progress and grows frustrated. Blake leaves after reassuring her of his support without conditions. Daemon, despite his resentment, prepares her food and shows a mix of care and jealousy. They talk about the training and the risks, but leave the events of the previous night unresolved. Daemon asks her to keep distance from Blake and leaves alone.
Chapter 20 Summary – Onyx – Training, Control, and Choice
As days and weeks pass, Kat trains with Blake while Daemon maintains a cold and watchful distance. The exhaustion mounts, her social life fades, and rumors confuse her friends. Blake advances patiently, explains the Source, and helps Kat move objects intentionally—she even freezes a knife thrown at her. The success brings both pride and fear, triggering Daemon’s protective fury as he nearly loses control. After the incident, Daemon demands an end to the training and argues with Kat about risks, responsibilities, and boundaries. Kat insists on continuing to protect her mother and the Luxen, believing mastering her powers is necessary. The conversation turns harsh as Daemon demands an immediate choice. Unable to give in without betraying herself, Kat stands her ground. Daemon shuts down emotionally and decides to leave, resulting in a painful break and a decision that will carry serious consequences for them both.
Chapter 21 Summary – Onyx – Suspicions, Training, and Uncomfortable Truths
Daemon vanishes from school, leaving Kat downcast. Blake accompanies her to the auditorium and they talk about what happened: Blake admits Daemon cares about her and apologizes for the tension. Kat avoids revealing who healed her, though she learns the strength of the Luxen who heals influences the power of the mutated human—emphasizing Daemon’s importance. With him absent, training progresses: Kat learns to freeze objects thrown at her and to channel emotions like fear. Blake remains patient and understanding, makes it clear he expects nothing romantic, and respects her feelings for Daemon. At school, rumors grow; Kat admits to Lesa that she likes Daemon, even if it’s “complicated.” At the end of the day, Kat sees Bethany—Dawson’s girlfriend—alive and escorted by a Department of Defense agent, a sight that changes everything.
Chapter 22 Summary – Onyx – Bethany, Defense, and a Dangerous Alliance
Kat confirms with Blake that Bethany is alive and in the Department of Defense’s custody, implying Dawson might have healed her and that both were captured by the Government. The possibility of an internal betrayal arises. Kat’s rage triggers an accidental whirlwind, revealing her growing power. Blake insists Dawson is probably dead and warns Kat not to get her hopes up, becoming disturbingly insistent. After Blake leaves, Kat contacts Daemon and tells him the truth. Daemon immediately grasps the implications and shifts into his Luxen state, determined to uncover who betrayed them and what happened to his brother. Kat notices a bruise caused by Blake but hides it to avoid retaliation. Daemon decides to investigate Agent Vaughn and plans to surveil him. Kat insists on joining him and becomes his partner. Together, they form a secret alliance to investigate the Department of Defense, leaving Blake out and establishing a new united front.
Chapter 23 Summary – Onyx – Surveillance, Betrayal, and an Impossible Truth
Kat and Daemon surveil Vaughn’s house after nightfall using her mother’s car. During the drive, they argue about Blake, training, and the growing distance with Dee, until Kat clearly explains why she needs to control her abilities—to protect herself and not rely on anyone. Daemon accepts her decision, even if it hurts. They watch Vaughn arrive with Nancy and witness something disturbing: an Arum enters the house without hesitation. The revelation confirms a secret collaboration between Defense and the Arum. Alarmed, they go to Matthew, who reveals the truth about Luxen healing, human mutation, and the irreversible bond that forms between a Luxen and the person they heal. They realize that if Bethany is alive, so is Dawson. Hope and fear mingle. Kat supports Daemon as they both understand rescuing Dawson will come at a terrible cost that will change their lives forever.
Chapter 24 Summary – Onyx – The Source Awakens and Blake’s Betrayal
Daemon decides to keep the possibility of Dawson being alive from Dee, bearing the weight alone. Kat continues training with Blake while she and Daemon investigate Vaughn’s disappearance. During a session outside the beta quartz field, Blake takes Kat far under the pretense of getting food and deliberately exposes her to an Arum to trigger an extreme emotional reaction. The attack happens and Blake disappears, leaving Kat alone and terrified. Cornered, Kat connects with the Source, unleashes devastating energy, and destroys the Arum on her own. The triumph turns to horror as she realizes Blake orchestrated the danger and was willing to let her die. Injured, exhausted, and furious, Kat demands to go home. Trust is completely shattered, and Kat understands that Blake represents a threat as great as the enemies he claims to fight—one she will now confront without hesitation.
Chapter 25 Summary – Onyx – Hidden Wounds and a Shared Refuge
Kat arrives at school in pain after the night with the Arum, hiding the severity of her injuries. Blake announces he’ll be away for the holidays, which brings her both relief and suspicion. At home, Daemon shows up early, notices her condition, and ends up healing her despite her resistance. The closeness reveals how deeply it affects him to see her suffer. Kat falls asleep in his arms, feeling protected for the first time in days. When she wakes up, her mother finds them together, triggering an awkward conversation about boundaries, rules, and supposed romances. Kat tries to maintain emotional distance, but the tension is evident. Later, Dee insists on spending time together and convinces Kat to go to the movies with her, Adam, and Ash. Amid uncomfortable jokes and jealousy, Kat realizes how much she’s missed her friend. The afternoon ends with a fragile sense of normalcy, right before the snow stops suddenly—signaling that something invisible and dangerous is approaching.
Chapter 26 Summary – Onyx – Domestic Suspicions and an Impossible Name
Christmas morning stirs painful memories for Kat, marked by her father’s absence and Will’s constant presence. While preparing dinner, Will casually mentions Dawson and reveals Bethany was his niece, shaking Kat completely. The revelation sparks distrust and ties together too many dangerous threads. Later, Kat freezes a bowl without thinking and suspects Will may have seen her, though he says nothing. The next day, the tree is already gone, deepening her unease toward him. Unable to ignore the coincidences, Kat starts to consider that Will might be connected to the Department of Defense. Her anxiety grows when Daemon shows up soon after and invites her out. Kat decides to trust him and tells him what happened, convinced that Will may pose a direct and silent threat inside her own home.
Chapter 27 Summary – Onyx – The Warehouse and the Trap Unveiled
Daemon takes Kat to an abandoned industrial park after discovering suspicious movements from Vaughn. He enters the building alone while Kat waits in the car. When a black SUV arrives, Kat decides to act and approaches the warehouse, where she’s intercepted by two armed agents. Pretending to be lost, she tries to hide her identity, but one of them wounds her to confirm she’s different. Vaughn arrives and takes control, ordering her capture and mentioning cages and rewards. Just when Kat believes Daemon has been caught, Vaughn reveals his true identity: Daemon in disguise. Releasing his full power, he eliminates the agents without leaving a trace. Daemon helps Kat up and decides they need to leave immediately. The revelation confirms that the Department of Defense is actively hunting the mutated—and the danger is no longer theoretical, but imminent and deadly.
Chapter 28 Summary – Onyx – The Aftermath of the Warehouse
Kat and Daemon return home after the warehouse confrontation, marked by the violence they witnessed and the certainty they’ve crossed an irreversible line. Sitting face to face, silence weighs more than any words as Kat recalls the image of men turned to ash and the sense of having erased evidence that will still leave questions. Daemon reveals what he found inside: cages with special chains, bloodstains, and clear signs of captivity—confirming the place was used to imprison Luxen and altered humans. Their conversation turns into a tense argument, filled with guilt and fear, fueled by the possibility that Dawson might be involved and the constant threat around them. Daemon admits to killing humans for the first time, explaining his emotional state. After parting ways, Kat spends days anxiously watching the house next door. A visit from Dee and an invitation to a party contrast with her lingering unease as Kat tries to reclaim a sense of normalcy that no longer belongs to her.
Chapter 29 Summary – Onyx – The Hidden Truth Behind Blake
During a sleepless night, Kat investigates local news and uncovers Will’s medical background, raising doubts about her mother and her own ability to face another loss. Driven by unease, she searches for information on Blake and finds articles about his family’s murder, eventually uncovering a direct connection to Brian Vaughn, a Department of Defense agent. Convinced she’s been deceived, she takes action and heads to Vaughn’s house, breaking in using her electrical powers. The interior feels cold and artificial, and in an office she finds a folder filled with hundreds of photographs documenting her and Daemon’s lives since they arrived in town. The feeling of constant surveillance sparks rage and a violation of privacy. Continuing her search, she finds money transfers and an address marked with the initials DB. Before she can escape, Bethany appears, displaying unstable powers and warning of imminent danger. Kat manages to get away but is followed by Daemon, to whom she finally reveals everything she discovered—reinforcing their alliance and mutual commitment.
Chapter 30 Summary – Onyx – Blake’s Betrayal Revealed
Daemon and Kat investigate the office building in Moorefield and confirm it’s protected by alarms and the same dark red stone, strengthening the theory that Dawson might be there. Though Daemon plans to return alone, he insists Kat attend Ash’s party to maintain some sense of normalcy. Later, Kat wakes up to find Blake in her room, triggering immediate fear. Blake apologizes for his past behavior and suggests going to a public place. During the ride, Kat finds a blood-stained watch piece in Blake’s truck that once belonged to Simon, confirming her suspicions. She tries to escape, but Blake subdues her using the Source and incapacitates her. At his house, Blake confesses he works for the Department of Defense, that Simon was handed over, and that Kat has always been part of an experiment to assess her potential. He reveals he acts under threat to protect Chris, his only real connection. Kat realizes the extent of the manipulation as she’s left trapped and vulnerable, with Blake determined to force her cooperation at any cost.
Chapter 31 Summary – Onyx – The Night Everything Breaks
The confrontation escalates when Dee and Adam burst in and Blake loses control, unleashing a blast that kills Adam and leaves Dee gravely wounded. Kat is devastated by guilt and horror, knowing Adam died trying to protect her. Vaughn and two Arum arrive, demanding the bodies. Faced with the threat, Kat’s latent power fully awakens, and an ancient force returns to her, surrounding her in light. Daemon arrives and helps eliminate the Arum alongside her, while Vaughn tries to escape and is killed by his own attack. Blake flees into the woods, but Kat and Daemon catch up to him. Though Blake admits his guilt and begs for mercy, Kat decides there have been enough deaths. Daemon lets him go with a final warning. Exhausted, Kat collapses and faces Daemon’s anger and pain, as he accuses her of not trusting him. The night ends with Daemon walking away, leaving Kat alone with her guilt, mistakes, and an irreparable loss.
Chapter 32 Summary – Onyx – Grief, Truth, and an “Us”
After the massacre, Kat returns home and helps Matthew clean the place where Adam died, confronting her guilt and grief head-on. Matthew tries to comfort her by reminding her she’s not responsible for Blake’s choices, but Kat can’t forgive herself. After hiding what happened from her mother, she spends the day lost in dreams and remorse until she decides to go to the lake—the place where everything feels clearer. There she reflects on death, betrayal, and the certainty that the Department of Defense will come for her and Daemon again. Daemon appears and takes her to his house, where after a tense but honest conversation, they confront everything that happened. Kat confesses her feelings, and Daemon admits that despite the anger and pain, he never stopped caring for her. They reconcile emotionally, accept that they are in this together, and define an “us.” Though the guilt doesn’t vanish, they find comfort in each other and decide to move forward cautiously, determined to do things right despite the chaos surrounding them.
Chapter 33 Summary – Onyx – Love Under Threat
Katy returns home at dawn, feeling guilty for her happiness but aware that she can’t stop living. Daemon stays with her, and the two agree to stay together in the face of the imminent threat from the Department of Defense. At school, Adam’s death is reported as an accident, and Katy struggles to balance her guilt with moments of hope alongside Daemon. However, the calm shatters when she’s called to the principal’s office: her mother has been in an accident. Will offers to drive her to the hospital, but during the ride he reveals his true self. Under the guise of comforting her, he tricks her and injects her with a substance that completely incapacitates her. Katy tries to summon the Source but can’t. As she loses consciousness, she realizes in terror that there are infiltrators everywhere and the danger is far from over. The chapter ends with Katy falling into darkness, betrayed again and utterly defenseless.
Chapter 34 Summary – Onyx – The Onyx Cage
Kat wakes up in extreme cold, with stabbing pain and blurry vision inside a metal cage, chained with shackles coated in a dark substance that burns her skin on contact. The place is a warehouse filled with similar cages, buzzing lights, and distant voices. When she tries to use the Source, she finds herself disconnected and defenseless. In the next cage, she meets Mo, a young human with psychic abilities, beaten and held by Daedalus—a division tied to the Department of Defense. Mo explains the site is used to transport and imprison uncooperative subjects and warns that Kat is there for a different reason. Two guards arrive and violently remove Mo. Kat tries to intervene and is punished with restraints that amplify her torment. The pain becomes constant and devastating for hours, pushing her to her physical and mental limits. Despite the extreme suffering, Kat clings to survival.
Chapter 35 Summary – Onyx – Will’s Deal
Will reveals himself to Kat as an infiltrator for the Department of Defense and the one assigned to watch her after her anomalous healing. He explains Project Daedalus—a serum combining human and alien DNA designed to create functional mutants—and admits to handing over Bethany and Dawson. The onyx mixed with other stones keeps Kat incapacitated as Will lays out his plan to force Daemon into cooperation. His goal is to become mutated himself to escape disease and gain power. Daemon arrives at the warehouse and walks into the trap, unable to use his strength due to the onyx. Will offers a cruel deal: release Kat in exchange for Daemon mutating him and the promise of information about Dawson. Desperate, Daemon agrees to injure and heal Will, trying to limit the process. Kat is freed but realizes the sacrifice has bound them to an unpredictable enemy. The deal leaves an open threat and a final race against time.
Chapter 36 Summary – Onyx – Dawson Comes Home
Kat and Daemon flee the warehouse with time running out and head to the office building Will indicated. During the drive, Kat reflects on the torture she endured, the use of onyx, and how the experience has shifted her moral compass, leading her to accept extreme choices to protect those she loves. Daemon refuses to leave her behind and shares his fear of losing her, reinforcing their bond. Upon arrival, they find a building rigged with onyx and signs of an elaborate trap. They reach a room with an empty cage and realize Dawson is not there. The disappointment hits Daemon with crushing force, reopening the wound of losing his brother. They return home in silence, haunted by the feeling they’ve been deceived. But hope returns when Dawson suddenly appears on the porch, marking a turning point for them all.
Conclusion – Onyx
When everything breaks, only one thing remains: the truth. Love isn’t safe, power isn’t a gift, and loyalty might cost you the one thing you can’t bear to lose. In Onyx, Jennifer L. Armentrout leaves us on the edge of a new war, with Kat stronger, more wounded… and more alone than ever. The second book in the Lux Series doesn’t offer happy endings—only burning promises yet to be fulfilled.
This book summary by chapter ends just as a new darkness looms, when the most anticipated return becomes a looming threat. But one thing is clear—Daemon and Kat can no longer pretend to be who they once were.
What comes next is the ultimate test: powers out of control, secrets without mercy, and a long-lost brother who may never have wanted to be saved. Opal Book Summary by Chapter ➤
FAQs – Chapter by Chapter Summary – Onyx
What happens to Katy after Daemon heals her in the first book?
After being healed by Daemon, Katy begins to experience uncontrollable changes—physically, emotionally, and energetically. She starts developing Luxen-like powers, such as telekinesis and energy surges, which make her a target for both the Arum and the government. These changes force her into a world of secrets, surveillance, and brutal training where survival depends on mastering a power she never asked for.
Why is Blake considered a threat in Onyx?
Blake enters as a charming, human love interest but is later revealed to be a mutated human working for the Department of Defense. He manipulates Katy emotionally, exposes her to lethal danger, and causes Adam’s death. His betrayal shows that the real enemies aren’t always alien—the most dangerous ones are human, driven by fear, loss, and government coercion.
How does the bond between Katy and Daemon evolve in this book?
While their bond begins as an alien side effect from the healing, Onyx deepens it into something emotional and raw. Both struggle to separate real feelings from the trace, but their connection—rooted in loyalty, jealousy, grief, and trust—becomes undeniable. By the end, it’s not just about powers or proximity. It’s about choosing each other, even when everything else is falling apart.
What is the Department of Defense's role, and what do they want from mutated humans?
The DoD is the hidden villain of Onyx, operating secret experiments on humans healed by Luxen. They aim to control or eliminate these mutated individuals, fearing their unstable powers. Through Project Daedalus, they kidnap, torture, and weaponize those like Katy. Their agenda isn’t just control—it’s exploitation of power at any cost, even human life.
What impact does Dawson’s return have on the story?
Dawson’s reappearance is both emotional and strategic. For Daemon, it confirms hope against all odds; for Katy, it validates their worst fears about the government’s cruelty. His return signals that Project Daedalus is far more dangerous than anyone imagined, setting the stage for a larger war—one not just of species, but of freedom versus manipulation.
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