|If you'd been in our place that day... you probably wouldn't have breached the Wall. Unlike us...|
|— Annie Leonhart acknowledges her new comrades' compassion|
Theo Magath and Hange Zoë spy on the Yeagerists that have taken over the harbor when they notice plumes of steam on the horizon. Realizing that the Wall Titans have reached Marley, they regroup with the remnants of the Survey Corps and the Warrior Unit to plan their next move. As Floch Forster threatens Kiyomi Azumabito and her engineers, Armin Arlert and Connie Springer try to obtain the Azumabito family's flying boat without bloodshed.
However, their plan goes awry when Kiyomi attacks Floch and provokes the Yeagerists into retaliating. Mikasa Ackerman is forced to break into the building to defend her, revealing herself and her companions as traitors to the Yeagerist cause. Connie kills his former classmates from the Training Corps to secure the flying boat while Reiner Braun and Annie Leonhart transform into their Titans.
As the remnants of the Survey Corps and Warriors plan their next move, both Hange Zoë and Theo Magath spy on the Yeagerists occupying the harbor. When Magath is surprised that the flying boat is still intact, Hange theorizes that the Yeagerists are keeping it because they do not want to lose the technology that the Azumabito family possesses. However, they would likely destroy it if they knew of the group outside the harbor. Even with the power of the Titans, stopping them will be hard.
The group deliberates over their attack plan and the casualties that will likely happen. Annie Leonhart is initially unconcerned about the Azumabitos, but Onyankopon plans to have their engineers prepare the flying boat because, without them, it is a wingless ship. Both the boat and the Azumabitos have to be protected.
However, the Survey Corps members would like to avoid killing the Yeagerists, which presents the group with a conundrum on how they could accomplish all their objectives. Connie Springer protests and Armin Arlert does not volunteer an alternate plan. Annie muses over how the Survey Corps members would not have chosen to destroy the wall, unlike the Warriors, if they had been in the situation the Warriors were. Reiner Braun remembers when Eren told him how he was just like Reiner. He wonders if that was what Eren had meant. Annie and Reiner mutually decide to let the Survey Corps sit out the fight. However, Hange is not interested in sitting out themselves. They spotted the Wall Titans crossing the ocean and believe the Titans have already arrived on the northeastern part of Marley, destroying the nearest cities.
Magath pushes his way over to Yelena and covers her mouth while he breaks her arm. He demands that she reveal where Eren Yeager is hiding. Yelena responds that if they bring her along, she might tell them where. Onyankopan is against torturing her, but Magath only stops after seeing Gabi Braun watching him. He then apologizes for his behavior the previous night and admits that Paradis Island residents should not be judged for their ancestors' actions. Magath then addresses the Warriors and agrees they should not be burdened by the world's hatred either, but he considers it his responsibility to ensure that future generations are aware of their history and for that, they will need to stop Eren. He asks the Survey Corps to overlook his actions, but Armin refuses because they are getting their hands dirty.
As Floch Forster looks out the window of the building where he is holding the Azumabitos, he doubts history has ever changed as much in one day as it has now. Hizuru will be wiped out along with the rest of the world and paints it as a benefit to Kiyomi Azumabito since the world will reborn without other troubling matters. She and her engineers just need to contribute to the island, especially if she does not wish to lose any more men.
Kiyomi says he is just making the world a smaller place and that they will continue to kill each other as usual. Floch brushes it aside and says that it is important to know one's place, and if it comes to it, they do not need the Azumabitos' technology. He points the barrel of his gun to her temple as he reiterates the necessity of knowing one's place.
However, his discussion with her is cut short by the arrival of Armin and Connie on horseback. They call out to him under the pretense of chasing the Cart and Armored Titans, who had fled south. Armin says they need the Azumabitos to prepare the flying boat so that they can follow them. Floch is confused, and Armin plays up the urgency by claiming that Jean and Onyankopon have been killed. When Connie points out the boat, Armin makes one last shout for Floch to send the engineers before they ride over.
The two of them are surprised to find their former Training Corps friends Daz and Samuel have joined the Yeagerists and that the flying boat has been rigged with explosives. Armin presses Samuel and Daz to disconnect them with the same urgency he used with Floch, but Samuel tries to calm him down, saying that there are suspicions that Connie and Armin are working with Marley. They dispute that, pretending to take offense, and Samuel and Daz are relieved. Despite his misgivings, Daz decides to listen to Armin and Connie and disconnects the explosives from the detonator. Armin is anxious, since this means that all they need are the engineers and then they can accomplish their mission without bloodshed.
Floch does not buy Armin and Connie's story, though. Inside the building with his hostages, he decides that he will eliminate his concerns and aims his gun at one of the engineers. Kiyomi intercepts him as he fires, saving the engineer, but not before everyone notices the sound of gunfire. Floch calls for other Yeagerists to kill her, but Mikasa Ackerman dives in through a window to protect Kiyomi. In the fight, Floch manages to escape outside, and alerts the Yeagerists about the traitors among them. Mikasa realizes they are going to shoot Thunder Spears into the building and herds the Azumabitos towards the basement where they meet up with Jean Kirstein, Hange, and Magath.
Seeing the ruckus break out, Daz begins reconnecting the explosives. Armin tries to stop him, but is shot by Samuel. When Connie tries to help him, Samuel tells him not to move. He urges Daz to hurry and blow up the boat. Connie tries to reason with him, but Samuel brings up the old conversation the 104th Training Corps had about taking more land for themselves and sharing meat together. Upset, Samuel wonders how it has come to this.
Kiyomi and Floch independently consider the usefulness of hiding in the basement, and the reason for that positioning becomes clear when Reiner and Annie transform into their Titans. As the Armored and Female Titan fight the Yeagerists, Connie struggles with Samuel, who he tackled during their surprise attack. Armin regains consciousness, enough to try stopping Daz from rearming the explosives. Frightened, Daz grabs his gun and points it at Armin's head. Samuel calls Connie a traitor and brings up how they should be on the same side, which reminds Connie and Armin of the questions they had of Bertolt Hoover when he and Reiner had tried to kidnap Eren.
Connie screams and yanks away Samuel's gun, which he uses to kill Daz, saving Armin's life. He then kills Samuel as well, with tears in his eyes.