Book Summary – Sentinel – Covenant Series – Book 5
- Jason Montero
- 3 days ago
- 18 min read
Updated: 1 day ago
The blood of gods never spills without consequence, and when love defies the divine, the price is one’s own humanity. In Sentinel, the fifth and final book of the Covenant Series by Jennifer L. Armentrout, Alex awakens scarred — not only in flesh, but in soul. What once was duty has become destiny, and what once was love becomes the only anchor between oblivion and the divine.
Enemies no longer hide in shadows: Ares, the betrayer, walks among mortals, and Seth, bound to Alex by their link, teeters between redemption and ruin. Through each chapter of this book summary by chapter, we uncover a war where titans rise, myths fall, and death ceases to be an ending — it becomes legend. Akasha ignites, power shifts, and the heart of a warrior becomes the most dangerous weapon of all.
But to understand how this destiny began — and why only Alex can end it — we must return to the first strike, the first scar, the first awakening. To experience the full divine arc, start from the beginning here: Reading Order of the Covenant Series ➤
Chapter-by-Chapter Summary
Chapter 1 Summary – Sentinel – The Awakening After Ares’s Betrayal
Álex wakes in a room of the Covenant in South Dakota with her body shattered and her mind fragmented after Ares’s attack, who had been hiding under the identity of Romvi. The deaths of Dominic, the dean, and several Guards weigh heavily on her, along with the fear that Ares will return. Aiden stays by her side, exhausted and injured, determined to wait for her as long as it takes. The bond with Seth reappears and a surge of energy shakes her, allowing her to open her eyes. Then she discovers irreversible changes: extensive scars and glowing amber eyes that terrify her and alarm Aiden. Though she considers fleeing with him, she understands she cannot abandon her duty, for stopping Ares is vital to prevent chaos. The fear of her transformation and the power awakening within her mixes with the deep love she feels for Aiden and the certainty that the future will be brutal.
Chapter 2 Summary – Sentinel – Decisions Under the Threat of Seth
Álex faces the tense gazes of Guards, Sentinels, and allies, aware of her change and the danger it represents. Almost three days have passed since Ares’s attack and security has been reinforced, although suspicion of a traitor persists. Álex admits that Seth can locate her through the bond, which intensifies the conflict with Aiden, who refuses to let her run. News of deadly wars confirms that Ares is provoking discord on a global scale to strengthen himself. After a tense debate, Álex agrees to stay at the university and allow everyone to fight alongside her, understanding that she will need an army. The decision reveals Aiden’s leadership and the collective commitment in the face of a divine threat. Though fear persists, the group assumes that war is inevitable and that resisting united is the only option against Ares and the danger Seth represents.
Chapter 3 Summary – Sentinel – The Void After the Funerals
Before organizing the resistance, the community honors the dead in a solemn funeral where half‑bloods and pure‑bloods remain separate even in mourning. Álex feels a disturbing disconnection, unable to experience full emotions except fear and pain. After the ceremony, her anxiety increases and the bond stirs, amplifying sounds and sensations to the point of near collapse. Aiden accompanies her, acknowledging that not everything is right and encouraging her to accept her fury and sadness. Contact with him manages to partially break the numbness, reminding her that she can still feel something real. However, emotional fragility persists and the need to cling to Aiden becomes urgent. Just as dawn advances and the crowd returns to campus, a security alarm blares, announcing a new attack and cutting off any attempt at calm or emotional recovery.
Other Books or Series – Jennifer L. Armentrout
Blood and Ash
Flesh and Fire
Lux
Covenant
Titan
The Dark Elements
Harbinger
Wicked Trilogy
The Vincent Boys
Wait for You
Frigid
Awakening
Chapter 4 Summary – Sentinel – The Barrier Falls
Sirens confirm an attack on the campus barrier and Álex accompanies Aiden to the front despite not being healed. Possessed birds strike first, leaving Sentinels dead and wounded, until Álex and Aiden combine fire and air to destroy them. Then, a horde of daimons assaults the gate, forcing a desperate defense. In the chaos, Álex is frozen by visions of Ares, but Artemis’s intervention turns the tide and halts the massacre. The goddess warns that Ares continues to move pieces and that Seth is active, besides sensing something strange within Álex. After the battle, the campus is marked by blood and exhaustion. Watching Aiden care for a wounded comrade, Álex understands that both are exhausted and that the war has just begun, leaving behind any illusion of a simple life.
Chapter 5 Summary – Sentinel – Suspicions, Fear and the Possibility of an Impossible Future
Álex rests beside Aiden after the attack, wearing his clothes and seeking normality amid the chaos, but unease won’t let her sleep. The closeness between them restores her sense of security and calm, and Álex confesses the fear she felt when she froze during the battle and the guilt for not reacting sooner. Aiden comforts her, reminding her that she is strong, human, and not alone in the war approaching. As intimacy grows, a conversation interrupts the moment: Artemis and other gods hinted that there is something inside Álex. Aiden proposes the possibility of a pregnancy, an idea that at first seems absurd, but soon plants real doubts. The notion changes everything, from the war to their relationship and the future of the world. Though fear dominates, a spark of hope rises at the thought of a shared child.
Chapter 6 Summary – Sentinel – Preparations, Memories and the Weight of Leadership
The next morning, Álex wakes after a night of nightmares and persistent thoughts about the possible life growing inside her. She decides to change her appearance and visits Olivia, who cuts her hair and offers a sincere conversation about the war, Seth, and Ares. The gesture gives Álex back a sense of control and human closeness she had lost. Aiden reappears attentive, making sure she eats well, reinforcing the suspicion they both avoid naming. Soon after, Álex dons the Sentinel uniform, though she no longer feels part of that role, and heads to the Council meeting. Facing a crowd divided by prejudice, Álex confronts the disdain of some Ministers and defends the half‑bloods with firmness. Her speech exposes Ares’s real threat and forces everyone to listen, just as a silent alarm shakes her inner bond.
Chapter 7 Summary – Sentinel – Seth’s Return and the Betrayal That Demands Blood
Álex feels Seth’s presence within the campus and leaves the Council despite the warnings of Aiden and Marcus. Guided by the bond, she reaches the gates and confronts him, discovering that he controls the Guards through compulsion. Seth appears remorseful and claims he did not know what Ares would do, revealing that he brought Lucian with him as proof of his betrayal. Lucian is freed from the compulsion and exposed as a conscious accomplice to Álex’s suffering. The truth shatters any remaining restraint and Álex, dominated by cold fury, fires and kills Lucian without hesitation. The act shakes everyone and marks a point of no return. Seth is left in shock at the decision, while Álex admits she still does not trust him. Aiden intervenes and knocks Seth unconscious, prioritizing safety over any possible future alliance.
Chapter 8 Summary – Sentinel – Guilt, Visions and a Danger Born Within
Seth is locked up under the Council while Álex deals with the weight of having killed Lucian without feeling remorse. In the shower, she reflects on her loss of empathy and the fear of changing in an irreversible way. She seeks solace in Aiden, using physical closeness to escape the emotional void, but a vision of Ares bursts in and almost causes a tragedy when Álex mistakes Aiden for her enemy. The episode leaves her terrified of her own mind. Unable to sleep, she decides to visit Seth in the cells. There, he confesses his addiction to power, his remorse and reveals that Álex must become the God Slayer to stop Ares. Seth warns that holding that power too long could destroy her. Álex admits her fear, her possible pregnancy and her mental instability. In front of Seth, she understands that they are both weapons created by gods and that the real danger may be growing within her own self.
Chapter 9 Summary – Sentinel – The Gods of Fear Come to Light
Álex talks with Seth and discovers that her father is still alive in the Catskills, protected among servants while Ares keeps him as a future threat. The revelation awakens anguish and reinforces the certainty that Ares will use everyone against her. After leaving, Álex confronts Aiden for having gone to see Seth, unleashing an argument filled with jealousy, pain, and unspoken confessions. Later, Apollo bursts into the dean’s office and, sensing something strange within Álex, forces a brutal revelation: Phobos and Deimos, Ares’s sons, have been inside her since the battle. The twins emerge like white smoke, mocking her and announcing death before vanishing. Apollo explains that they were feeding on her emotions, manipulating them. Realizing she was not losing her sanity, Álex’s rage explodes uncontrollably and her power begins to overflow dangerously.
Chapter 10 Summary – Sentinel – Unleashed Fury
Overwhelmed after the expulsion of Phobos and Deimos, Álex flees and locks herself away, unable to contain the emotional avalanche she has suppressed for weeks. Rage, pain, and loss erupt as pure power, destroying the room as Akasha’s energy manifests without limits. Seth bursts in and tries to calm her, but Álex channels her fury into beating him mercilessly, using combat as a physical release. Seth does not defend himself, allowing her to release everything she has been carrying inside. The outburst ends in tears, exhaustion, and a gradual calm, sustained by the connection between them. Seth admits he understands her pain and confesses that he cannot forgive himself for his indirect role in what happened. When Álex regains control, she faces Aiden and Marcus, who receive her with relief. Alone with Aiden, Álex takes refuge in his embrace, recovering clarity, stability, and the feeling that she has returned to herself.
Chapter 11 Summary – Sentinel – The Impossible Plan
With Phobos and Deimos gone, the group meets with Apollo and Athena to devise a plan against Ares. Athena reveals that the only viable option is to free Perses, the Titan of destruction, to train the God Slayer and gain a strategic advantage. The idea inspires fear but also hope, since Ares would not expect it. Álex accepts the risk despite understanding that it could worsen the war. Later, exhausted, she retreats to her room and finds comfort in Aiden, sharing everything she had kept silent. Together they reconcile their fears, jealousy, and wounds, reaffirming their love and commitment. Calm slowly returns, and Álex realizes that she no longer wants to die. As she sleeps beside Aiden, she accepts that the future will be brutal, but also that she remains a fighter willing to face whatever comes, even if that means freeing a Titan and defying the fate imposed by the gods.
Chapter 12 Summary – Sentinel – The Price of the Underworld
The meeting with Hades confirms the magnitude of the risk: freeing Perses could unleash deadly wars between humans and gods, as the Titan thrives on absolute destruction. Even so, Álex defends the decision, comparing his threat to that of Ares and standing up to Hades without backing down. The god of the Underworld warns that Perses can kill an Apollyon and cannot be destroyed. Despite this, the group holds its position, accepting the danger as the only alternative. Finally, Hades reveals his condition for releasing the Titan: he demands Aiden’s soul as payment. The revelation shakes everyone, cutting away any remaining lightness and making it clear that every step against Ares will carry a devastating cost. Álex understands that the war will demand not only collective sacrifices, but personal decisions capable of shattering everything, and that the price of victory may be losing the man she loves.
Chapter 13 Summary – Sentinel – The Pact That Changes Destiny
Álex confronts Hades and refuses to surrender Aiden’s soul, but understands that Perses is the only way to stop Ares. Aiden accepts the bargain and agrees that his soul will belong to the god of the Underworld after his death, embracing an irreversible sacrifice. Before leaving, Álex negotiates a decisive condition with Apollo: the liberation of the half‑bloods, the abolition of the laws that force them into service, and the end of the Elixir. Apollo agrees and promises to change the order of the races when everything is over. The decision shocks everyone and offers a different future to entire generations. With the agreement sealed, Hades organizes the journey to Tartarus and designates Álex, Aiden, and Seth as responsible for Perses. Though fear persists, Álex realizes that she has used her power not only for war, but to transform the system that had oppressed her people for centuries.
Chapter 14 Summary – Sentinel – The Path to Tartarus
After their farewells, the group descends into the Underworld through Hades’s power and approaches Tartarus on horseback. Álex observes the dead, the condemned Guards, and the daughters of Danaus, understanding the weight of eternal punishments. Tension grows between Aiden and Seth, marked by jealousy and old wounds, as the environment becomes increasingly hostile. The landscape transforms into fire, sulfur, and destruction, revealing the true nature of Tartarus. The group crosses zones of torture and punishment, recalling the cruelty of the gods. Finally, they reach the Tombs of Tartarus, where the Titans sleep beneath ice and ancient symbols. Hades explains their imprisonment and guides the group to Perses. Álex, flanked by Aiden and Seth, senses the latent danger as the ice breaks and the Titan awakens, marking a point of no return.
Chapter 15 Summary – Sentinel – The Awakening of Perses
In the Tombs of Tartarus, Perses awakens, revealing an intimidating and powerful presence. Hades proposes a deal: help defeat Ares in exchange for his release into the Elysian Fields. Perses mocks them, provokes, and shows his contempt for gods and mortals alike, but acknowledges his hatred for Ares and his desire to confront him. Álex lays out the war, the destruction of mortals, and the global threat, though the Titan makes it clear that he does not care about humanity. After tense exchanges, Perses accepts with a personal condition that unsettles the group. Hades confirms the agreement under threat of eternal punishment should he betray the pact. Though the alliance is sealed, Álex perceives the immense risk of unleashing such a volatile force. The deal is set, knowing that Perses is not a savior, but an unpredictable weapon.
Chapter 16 Summary – Sentinel – The Truce in Las Vegas
The group travels to Las Vegas to grant Perses a night of indulgence before the final confrontation. The city remains unaware of the global chaos, which unsettles Álex. Perses provokes conflict among mortals with his mere presence, confirming his destructive influence. Seth offers to watch over him and leaves with the Titan, leaving Álex and Aiden alone. Seth’s emotional tension seeps through the bond, causing unease in Álex. Alone together, Álex and Aiden share a moment of intimacy that restores calm and connection, pushing away for a few hours the war, the sacrifice, and the fear of the future. Aiden reaffirms his love and restores the security Álex had lost after Perses’s words. As they enjoy that private truce, both know that the peace is temporary and that the battle against Ares is inexorably approaching.
Chapter 17 Summary – Sentinel – Tensions Before the Battle
Álex wakes up startled and discovers that Perses and Seth returned drunk after fighting daimons, provoking both relief and confusion. Later, Álex and Aiden share an intimate moment that strengthens their bond before the war changes everything. At noon, Hades transports them to the Covenant and Apollo appears to coordinate the plans. Perses demands to begin training immediately and warns that Ares already knows of his presence, giving them only one week. They decide to attack in the Catskills the following Monday. Training with Perses proves brutal and humiliating for Álex, Aiden, and Seth, who fall again and again before the Titan’s strength. Álex realizes she is not ready to face Ares but also knows she must learn fast. The chapter ends with Perses demanding she get up after another defeat, making it clear that weakness will not be tolerated.
Chapter 18 Summary – Sentinel – Decisions and Promises
Training leaves Álex, Aiden, and Seth covered in wounds, while the army progresses under Perses’s ruthless discipline. In private, Álex and Aiden talk about the upcoming battle and make a painful decision: Aiden will not be by her side when she faces Ares, to avoid becoming a vulnerability. Though it hurts, Aiden understands and promises to stay with the army. They also discuss the power transfer from Seth, which remains postponed. Later, a meeting covers the strategy against Ares and the need for postwar reconstruction, leading Marcus to accept staying at the Covenant as its leader. Afterwards, Álex confronts Apollo and forces him to admit that the gods must get involved in the war. Apollo agrees to try involving them, sparking real hope. The chapter ends with the sense that the conflict is no longer just a mortal one, but a fight involving all sides.
Chapter 19 Summary – Sentinel – The Limit of Power
Training intensifies when Perses removes the mats and forces them to fight on hard ground. Álex fights with greater clarity and realizes that no one forbade them from using their Apollyon abilities. Using akasha, she manages to bring down Perses, proving that strategy and power combined can overcome even a Titan. Perses confirms that this was the lesson and ends the session. Afterwards, Álex seeks out Seth to demand the power transfer. In the cemetery, Seth reveals the burden he carries as the First and confesses his ongoing struggle with the need to transfer the power. The argument escalates until Seth loses control and destroys a statue with akasha, revealing his fear of what Álex could become. Seth leaves, refusing to perform the transfer yet. The chapter ends with the certainty that time is running out and the tension between them threatens the balance before the final confrontation.
Chapter 20 Summary – Sentinel – The War Begins
The convoy departs for the Catskills under a gray sky and an atmosphere heavy with omens. Álex says goodbye to Marcus, who expresses his pride and asks her to return alive. The journey passes without incident, heightening their unease. Upon reaching the mountains, Perses senses violence in the air and soon the earth opens, giving rise to the Spartoi, warriors born from the ground in Ares’s service. Battle erupts immediately. Álex, Seth, Aiden, and their allies fight effectively, learning they must decapitate the enemies to defeat them. Perses enjoys the battle with unsettling ferocity. When automatons appear, the fight turns chaotic. In the midst of the clash, Olivia is struck by an axe and vanishes instantly. Her death shakes everyone and emotionally breaks Álex, who falls to her knees as the battle continues, marking the real and brutal beginning of the war.
Chapter 21 Summary – Sentinel – Grief, Hope and the Impossible Return
After Olivia’s death, the group is forced to continue without time for farewells, driven by Perses’s coldness and the urgency of war. Álex travels in silence, consumed by grief, clinging to the idea that Olivia is with Caleb in the Underworld. Upon arriving in the Catskills, they discover a much larger camp of Sentinels who have managed to evade the automatons, bringing unexpected relief. Solos explains that they have gathered forces from the New York Covenant and obtained key information about Ares. Álex regains hope upon learning that some servants are no longer under the Elixir, reviving the possibility of finding her father alive. As the camp prepares, emotional tension grows and guilt weighs on everyone. Álex tries to remain strong, knowing she cannot afford to fall apart, even though the grief remains and the battle draws near.
Chapter 22 Summary – Sentinel – The Reunion That Gives Meaning to Everything
Álex faces a revelation that eclipses any previous fear when she reunites with her father, alive and turned into a Sentinel. Emotion overwhelms her as she confirms he escaped the Covenant’s control to find her after hearing about the arrival of the Apollyon. Unable to speak normally, Álex communicates with him through gestures and notes, discovering that Laadan kept him informed about her life. Her father expresses pride, acceptance, and love, healing old wounds and confirming that her sacrifice has not been in vain. The reunion is completed by Aiden’s arrival, whom her father watches cautiously but accepts as an essential part of his daughter’s life. Despite the joy, reality sets in when her father decides to return to protect other servants. Álex says goodbye with pain, clinging to the promise of a possible future after the war.
Chapter 23 Summary – Sentinel – The Beginning of the Final Assault
At dawn, the army advances toward the Covenant under a deceptively calm sky. Álex prepares for battle alongside Aiden, Seth, and Perses, aware that each step brings them closer to a point of no return. The plan begins as they separate from the main army, leaving the others as a distraction in front of the walls defended by automatons and mortals. Álex says goodbye to Aiden with a kiss full of love and fear, accepting that they cannot fight together. With Seth and Perses, she descends toward the eastern flank and faces daimons in a brutal fight where elemental power proves decisive. After breaching a wall opening, they eliminate automatons and move through the ravaged Covenant. The appearance of the Olympian gods confirms that Apollo kept his word. When Perses disappears to face Ares alone, Álex and Seth press on, knowing the confrontation is imminent.
Chapter 24 Summary – Sentinel – The Power of the God Slayer Awakens
Inside the Covenant, Álex and Seth face soldiers under compulsion, forced to kill them to survive, leaving a deep emotional toll. They move through hallways marked by past violence until they hear Perses provoking Ares, confirming he has not abandoned them. After eliminating a controlled Sentinel, Seth leads Álex to a secluded room and decides they can wait no longer. There he begins the power transfer, guiding Álex through ancient words that awaken absolute forces. Energy flows between them, transforming their bond and unleashing immense power that floods Álex’s body without loss of control. The process ends when the bond breaks and the power returns to her completely. Álex floats, renewed and confident, aware that fear no longer rules her. For the first time, she knows with certainty that she is ready to face Ares and fulfill her destiny.
Chapter 25 Summary – Sentinel – The Price of Defeating a God
Álex bursts into the ballroom engulfed in Akasha and confronts Ares alongside Seth and Perses, fully aware that this battle will decide everyone’s fate. The fight is brutal, physical, and devastating, with Ares proving why he remains an Olympian even when cornered. Perses is gravely wounded and Seth is thrown against the columns, forcing Álex to face the final confrontation alone. When Ares tries to break her by threatening Aiden and her father, Seth intervenes at the crucial moment, creating the opening they need. Álex unleashes her full power, merging her strength with Seth’s through their restored bond, and releases an explosion of Akasha that consumes Ares completely. Victory comes with the fear of having lost Seth, who wakes seconds later. But the calm is short-lived: the eleven Olympians appear and Zeus decrees that the God Slayer cannot exist, forcing Álex to accept her death to protect those she loves.
Chapter 26 Summary – Sentinel – Paradise Does Not Replace Life
Álex awakens in the Underworld, aware that she has truly died and been taken directly to Hades’s palace. There she realizes there will be no second chances or divine favors and is led to the Elysian Fields, a paradise shaped by each soul’s deepest desires. Though the place is beautiful and functional, the absence of Aiden turns eternity into something unbearable. Álex creates a paradise inspired by Deity Island and discovers that even in death, she still feels emotions, memories, and loneliness. Her body appears restored, without scars or marks, but the gift cannot make up for the loss. Caleb stays by her side, trying to help her avoid the Valley of Mourning, encouraging her to live within the afterlife. Still, Álex understands that no matter how perfect the paradise, it cannot offer her the one thing she truly desires: to love Aiden and live beside him, something no heaven can replace.
Chapter 27 Summary – Sentinel – Death, Immortality and Eternal Love
Álex reunites with Apollo in the Covenant garden and learns the consequences of her sacrifice: the fall of the Elixir, the Council’s reform, and the devastating pain her death caused Aiden and the others. Forced to perform a symbolic ritual, she launches a spirit boat into the sea to bid farewell to her mortal life and move on. At that moment, Aiden appears, alive, real, and present in the Underworld, revealing that he is not an illusion. Apollo explains that Álex drank ambrosia before dying, which made her immortal after a mortal death, forcing her to split her existence between the world of the living and the Underworld. Furthermore, Seth sealed a final pact: he surrendered his servitude to the gods and secured Aiden’s immortality, sacrificing himself completely. Freed from the destiny of the God Slayer, Álex accepts her new life with Aiden. Together, they understand that their story does not end, but transforms into a legend meant to be told for eternity.
Conclusion – Sentinel
Some wars are won with swords, and others through unseen sacrifices. In Sentinel, Jennifer L. Armentrout doesn’t just close a series — she forges a legend that transcends time. This chapter-by-chapter summary has led us from the first scar to the final breath, proving that death is not always an end… sometimes, it’s the beginning of a shared eternity.
Alex is no longer the girl who woke up at the Covenant. She’s been daughter, warrior, God Slayer, and ultimately, a symbol of change in a world torn by bloodlines. And when ambrosia bridges the gap between the mortal and divine, love knows no limits. Seth gives up his servitude. Aiden becomes immortal. And the universe finally bows to sacrifice.
Yet even after the last battle, the story doesn’t end… it simply transforms. If you want to keep exploring new worlds where the impossible becomes real and every fight reshapes fate, continue here: Other Series from the Blog ➤
FAQs – Chapter by Chapter Summary – Sentinel
Why is Álex’s transformation after Ares’s betrayal so important in Sentinel?
Ares’s betrayal marks the beginning of Álex’s irreversible change. She wakes up scarred, both physically and emotionally, and realizes that the power growing inside her is no longer just a tool—it’s a burden and a weapon. This transformation defines her path as the God Slayer, where each decision strips away her humanity and brings her closer to a destiny she can’t escape.
What makes Seth’s bond with Álex so dangerous throughout the story?
The bond between Álex and Seth goes beyond emotion—it’s a channel of power and vulnerability. Through it, Seth can locate her and influence her emotional state, which puts both of them at constant risk. As the war escalates, this connection becomes a liability, especially as Seth’s own instability threatens Álex’s mental and physical safety.
Why is the release of Perses considered such a turning point in the war against Ares?
Perses, the Titan of destruction, is an unpredictable force. While his hatred for Ares aligns with the protagonists’ goals, his contempt for mortals makes him a volatile ally. Releasing him means trading one threat for another, but it’s also the only way to train Álex to defeat Ares. His presence shifts the balance of power—and raises the stakes exponentially.
How does Álex's death reshape the story's ending and her ultimate fate?
Álex’s death is not the end, but a metamorphosis. Ordered by Zeus after defeating Ares, her sacrifice seals her destiny as a legend. But due to ambrosia and Seth’s final act of devotion, Álex becomes immortal and is granted a new existence alongside Aiden. Her death is not punishment—it’s a passage into a new myth, one forged by love and defiance.
What does Sentinel suggest about the cost of true change in a broken world?
True change in Sentinel doesn’t come from divine intervention—it comes from sacrifice. Álex and her allies don’t just fight a god; they dismantle centuries of oppression. From abolishing the Elixir to rewriting societal laws, the story shows that victory demands more than strength. It requires vision, pain, and the courage to tear down an unjust system.
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