|I wonder... was there any other choice we could've made? Maybe everything had been decided from the start. Still, I can't help but think: Back then, what if I had... given him a different answer?|
|— Mikasa Ackermann ponders her relationship with Eren Jaeger|
Mikasa Ackermann recalls the Scout Regiment's first trip to Marley, where they had joyful moments such as discovering ice cream and connecting with refugees from the Marley Mid-East War, but also disappointments, in that the Subjects of Ymir Protection Group was not the ally the Scouts hoped they would be. That was when Eren Jaeger left the Scouts and began operating on his own, telling them that he would follow his brother Zeke's plan. Mikasa wonders if they could have made choices so things would have turned out differently.
Meanwhile, Eren recalls the events that had led him here; how he had met Yelena and learned of Zeke's euthanasia plan, how he had confided in Floch Forster that he would only pretend to go along with Zeke's plan when in reality he would use the rumbling to wipe out the rest of the world, and how he had tried and failed to persuade Historia Reiss to fight or flee before the Military Police turned her into a Titan to eat Zeke. A fleet of ships tries to stop Eren's army of Wall Titans, but fails, and his Titans finally arrive at Marley's shores.
As the group trying to stop Eren Jaeger travels to Odiha, Mikasa Ackermann ponders whether Eren has truly changed. She comes to realize that he may have always been this way, and wonders what she saw in him.
Mikasa remembers how the Scout Regiment arrives in Marley for the first time, disguised as ordinary citizens, and how they marvel at seeing a city outside the Walls. Onyankopon greets them and offers to take them to Kiyomi Azumabito's place, but before they can get anywhere, Hange Zoë, Conny Springer, and Sasha Braus are distracted by a car, which they have never seen before. Mikasa asks Eren to say close to her since they do not know what to expect, but notices that he seems to be staring off into the distance.
Armin Arlelt runs up to Eren and also tries bringing him back to reality, remarking on how they are finally in the outside world, to which Eren distractedly agrees that they are on the other side of the sea.
Overall, the group does not succeed in not standing out, but Hange is amused and comments on how at least they will not be seen as "island devils." One by one the younger members of the Scouts succumb to trying out ice cream, and Mikasa offers a taste to Eren, who recognizes it from his father's memories. Eldians in the internment zone rarely get to eat any.
A pickpocket steals Sasha's purse, but is caught by Levi Ackermann. The boy is clearly an immigrant and unwelcome in Marley, with passersby declaring that he must have snuck aboard a ship. The hostile crowd suggests tossing him into the sea or smashing his hand as punishment. Sasha speaks up in the boy's defense, saying she got her money back, but the mob is set on making an example out of him, adding that he could be a Subject of Ymir.
Levi grabs the boy and prepares to leave with him. He tells the crowd that he never called him a thief, and only said that it was not the boy's purse. He says it belongs to the boy's older sister, which he says is Sasha. Hange then steps forward to back up the story and Sasha plays along.
The crowd does not buy it, causing Levi and the others to make a break for it. They finally stop running at the outskirts of the city where the boy slips away and waves in farewell, having taken Levi's money.
Kiyomi apologizes for what they went through when they finally arrive at her estate. She explains that as blood testing improves, countries are finding more Subjects of Ymir among them. Because of other nations' fear of Eldians, she thinks it will be difficult for the Scouts to establish friendly relations with them. Armin says they need to try regardless, because if they give up on peace then they will have to go along with Zeke Jaeger's proposal to sacrifice Historia Reiss and her children to hold off the rest of the world with the threat of the rumbling.
Hange agrees and brings up the Subjects of Ymir Protection Group that is holding a forum the next day. They plan to observe them and see if they could become potential allies for Paradis Island. Hange acknowledges the odds are both difficult and dangerous, but feels they have to try. It is at that moment that Mikasa realizes that Eren has left the room.
A tear runs down Eren's face as he looks at a migrant camp beneath the nighttime sky. Mikasa catches up to him, warning him that he is their enemy's primary target, but then she sees what he was looking at. The pickpocket is in the camp below, and waving up to them. When she asks what happened, Eren cryptically replies nothing yet.
He describes the camp to Mikasa as a place for people who have lost their homes to war. He compares their situation to that of the islanders. One day their lives changed, and everything was taken from them. Eren asks Mikasa why she cares about him so much; if it is because he saved her when they were children, or because they are family. Mikasa becomes flustered as Eren pushes, asking what he is to her, and she finally stammers that they are family.
Just then, an elderly man from the camp invites them to have a drink, and the rest of their companions catch up to them. The entire group goes to the camp, and despite not knowing the language, they enjoy the food, drink, and company of the migrants. When Hange, Levi, and Onyankopon find them, the group is largely passed out on the floor of the main tent.
The next day, the Scouts attend the forum held by the Subjects of Ymir Protection Group. Their speaker announces their plan to aid refugee Subjects of Ymir, painting them as victims of the Eldian Empire's forced interbreeding, but also directs the group's hate towards Paradis Island. When he calls the island their true enemy, the crowd applauds. At that moment, Eren leaves the group, and Mikasa in the present refers to that day as the day Eren left them. The letters he sent the Scouts after that said he would trust in Zeke's plan.
Mikasa wonders if there was any other choice they could have made, or if everything had been decided from the start. She wonders how things might have played out if she had given Eren a different answer.
Elsewhere, Eren wonders where this all began. He recalls meeting with Yelena and hearing about Zeke's euthanasia plan. He also told Floch Forster that the two of them should pretend to go along with Zeke's plan, but in reality Eren plans to destroy the world and all their enemies. Eren then spoke with Historia, warning her that the Miliary Police were pushing to turn her into a Titan to eat Zeke, but Historia did not intend on fighting them or running away. If it was the best chance for the island's survival, she would do it. However, even though she was fine with it, Eren declared that he was not.
Historia opposed Eren's plan to use the rumbling on the rest of the world, comparing their deaths to that of his mother. Eren agreed about the senselessness of their deaths, but said it is the only way to end the cycle of revenge and hate. When Historia said she would not be able to live with herself if she did not try to stop him, Eren suggested he would erase her memories once he had control of the Founder.
In Marley, Eren met with Zeke and asked about Mikasa's headaches. Zeke had never heard of any illnesses specific to the Ackermanns. He does not believe there is any proof they are driven to protect a host. Zeke thinks Mikasa's devotion to Eren is simply because she likes him. When Zeke asks Eren what he would say to her, Eren replies that he has only four years left to live. However, even after he is gone, he wants his friends to live happy lives.
In the present, a global fleet prepares to meet the army of Wall Titans crossing the sea. They fire on the swimming Titans, but it is not enough. When the Titans swim under their ships, the steam is enough to cook the crews alive and hurls the ships into the air.
Another line of defense in the form of artillery on the shore greets the Wall Titans as they emerge from the sea, but it is similarly ineffective, and the soldiers manning them abandon their posts and run. As they flee, a few turn around and see an even larger Titan following the Wall Titans, and declare that the Attack Titan has come.
As Eren marches into Marley, he remembers his mother's death and the vow he made that day- to keep pushing forward without stopping until he destroys every last one of his enemies in the world, while the Wall Titans make landfall and begin the destruction of Marley.
Currently Publicly Available Information
Beyond the Walls, there is a sea. On the other side of the vast, blue sea is a continent. That continent has cities, bustling markets, and all sorts of people living there, just like on the island. But in the outside world, Subjects of Ymir are despised more than anything.