Year 845, humanity has been living in the Walls safe for about 100 years. Then suddenly the Colossal Titan appears and destroys the Shiganshina Outer Gate. Then the Armoured Titan appears and destroys the Shiganshina Inner Gate. Eren’s mother is killed. Eren, Armin, Mikasa, and many others become refugees while 10 000 people die in the attack. Wall Maria is lost, humanity loses 1/3 of its land. Another 250 000 people are sent out on a suicide mission by the nobility to solve the food shortage.
2 years later they join the military. 3 years after that, they graduate. On the day of their graduation, the Colossal Titan shows up and attacks Trost District, the southernmost city of Wall Rose. People die. Eren almost dies but then somehow turns into a Titan. They convince the military that Eren is a good asset and are able to seal the hole using a giant boulder.
Most of the characters join the Survey Corps and head out on a mission to reach Shiganshina District, since they believe Eren’s father and the Basement might contain answers. Eren’s father disappeared around the time Wall Maria was attacked, and Eren has memories of his father injecting him with something.
On the expedition, a Female Titan appears that has intelligence. It kills a bunch of people. But the expedition is a trap and the Survey Corps manage to capture it. . . but it breaks free and almost escapes with Eren. Eren is rescued by Levi and Mikasa. They return to the Walls, defeated.
They figure out that the Female Titan was actually Annie Leonhart, a soldier in the Military Police, in disguise. They lay a trap for her, but it goes badly, and a battle breaks out in Stohess District. Ultimately they manage to stop her, but she seals herself within a crystal. The Survey Corps decide it will continue fighting for humanity, trying to solve all the mysteries, and defeat the Titans. The epilogue scene shows a crack in the Wall, revealing that there is a Titan inside the Wall.