|A girl I've never met before...molded my body out of earth. I was in an unknown land...and all I could do was watch. It feels like I was there...for years. But it also felt like it was over in an instant.|
|— Zeke Yeager tries to explain who saved him|
Floch Forster, Hange Zoë, and a number of Yeagerists are traveling to a Titan Forest when they hear the explosion caused by Zeke Yeager triggering a Thunder Spear. Zeke believes he is dying and he thinks back to his shared mission with Tom Xaver and his meeting with his brother, Eren Yeager. Before he dies, a mysterious Titan crawls up to him and tears open its belly, stuffing Zeke inside. Hange and Floch find the remains of Levi Ackerman as Zeke emerges from the Titan, fully healed.
Meanwhile, Yelena has Dot Pixis and other dissenting members of the military assembled in Shiganshina District. Eren goes to meet with the imprisoned Gabi Braun, to have her send out a distress call to Marley in exchange for saving Falco Grice. However, a disguised Pieck stabs the prison guard and pulls a pistol out, pointing it at Eren.
As Floch Forster and the other Yeagerists escort Hange Zoë, they hear an explosion off in the distance. As they ponder what it could be, Hange recognizes it as an explosion caused by a Thunder Spear. Zeke Yeager has been gravely injured to the point that only his head and part of an arm remains attached to his torso. He notices that the area around him is quiet and he realizes he is losing not only his hearing, but his vision as well.
As he lays dying, Zeke remembers his conversation with his friend and mentor, Tom Xaver, regarding how to get around Karl Fritz's vow to renounce war. If a Titan of royal blood comes into contact with the individual who possesses the Founding Titan, they will be able to draw out its power. However, Zeke would not be able to use the power himself. The decision would remain with the individual who possesses the Founder. Xaver tells Zeke to think of himself as a key and to find an individual he would trust with the Founding Titan.
Some time afterward, Zeke ate Xaver and became the new inheritor of the Beast Titan. He put on Xaver's glasses and called him "Dad," promising to find a suitable person for their plan.
As time passed, Zeke recruited Yelena and the Anti-Marleyan Volunteers. He learned that Eren Yeager possessed the Founding Titan and that Eren's father, a doctor, was missing. Zeke realized that his biological father had not died when he was sent to Paradis Island and that he must have acquired the missing Attack Titan. From there, Grisha must have fed the Founding Titan to Eren. Zeke realized that his father had done the same thing to Eren that he had done to Zeke, and so he promised Eren that he would rescue him.
Years later, they met up in Marley while Eren was pretending to be an injured soldier. Eren told Zeke about how he obtained his father's memories and how Grisha had killed the Reiss family to ensure he could take away the Founding Titan. Eren understood that if any of the Reiss children remained alive he could have been fed to them so they could regain the Founder, and that they were able to live because those children died. However, Eren told Zeke that he disagreed with Grisha's plan and that if the Eldians had never been born, none of them would have had to suffer. Eren agreed to cooperate with Zeke's plan.
After remembering that he gave Eren a baseball as a token of their agreement, Zeke begins to slip away, envisioning a young girl in tattered clothes, holding a bucket. One of the Titans he had created regenerates, and crawls up to his body. It rips open its abdomen and picks up what remains of Zeke, shoving it into the wound.
At Shiganshina District, Yelena and the Yeagerists have rounded up Commander Dot Pixis and the other Eldian military members and tied different colored cloths around the arms of the military. Pixis assumes this is to reveal who drank the infused wine and who could be deemed as a threat; after some banter, Yelena glares at Pixis and, due to not trusting Zeke, claims they must be punished for their actions.
Floch, Hange and the others approach the remains of the wagon and notice the Titan in the distance; Hange then spots a body near the river and despite warnings, goes over and is horrified to see that it is Levi Ackerman. Floch brushes it off as fortunate and goes to check for a pulse, but Hange reveals that he is dead due to absorbing the blast of a Thunder Spear detonation at point-blank range. Floch then notices the Titan begin to evaporate and a recovered Zeke steps out in a daze; Hange uses this opportunity to escape with Levi's body and jumps into the river. Floch asks Zeke what happened, and he recalls waking up in an unknown land, where a little girl rebuilt his damaged body out of the soil that surrounded him. He notes that it felt like it took years, but it was done almost instantly. Zeke concludes that what he experienced must have been the paths. He also reveals what happened to the Survey Corps soldiers that were escorting him with Levi and goes to meet up with Eren.
In a prison cell, Gabi Braun recalls the reactions of the Blouse family and is surprised when Eren appears with two Yeagerist members. He orders her to cooperate with him if she wants Falco Grice to survive, but then one of the soldiers plunges a knife into the throat of the other; the soldier is revealed to be Pieck and holds Eren at gunpoint as she closes the cell door.