Centuries ago, mankind was slaughtered to near extinction by monstrous humanoid creatures called Titans, forcing humans to hide in fear behind enormous concentric walls. What makes these giants truly terrifying is that their taste for human flesh is not born out of hunger but what appears to be out of pleasure. To ensure their survival, the remnants of humanity began living within defensive barriers, resulting in one hundred years without a single titan encounter. However, that fragile calm is soon shattered when a colossal Titan manages to breach the supposedly impregnable outer wall, reigniting the fight for survival against the man-eating abominations. After witnessing a horrific personal loss at the hands of the invading creatures, Eren Yeager dedicates his life to their eradication by enlisting into the Survey Corps, an elite military unit that combats the merciless humanoids outside the protection of the walls. Eren, his adopted sister Mikasa Ackerman, and his childhood friend Armin Arlert join the brutal war against the Titans and race to discover a way of defeating them before the last walls are breached.

After a horrific alchemy experiment goes wrong in the Elric household, brothers Edward and Alphonse are left in a catastrophic new reality. Ignoring the alchemical principle banning human transmutation, the boys attempted to bring their recently deceased mother back to life. Instead, they suffered brutal personal loss: Alphonse's body disintegrated while Edward lost a leg and then sacrificed an arm to keep Alphonse's soul in the physical realm by binding it to a hulking suit of armor. The brothers are rescued by their neighbor Pinako Rockbell and her granddaughter Winry. Known as a bio-mechanical engineering prodigy, Winry creates prosthetic limbs for Edward by utilizing automail, a tough, versatile metal used in robots and combat armor. After years of training, the Elric brothers set off on a quest to restore their bodies by locating the Philosopher's Stone—a powerful gem that allows an alchemist to defy the traditional laws of Equivalent Exchange. As Edward becomes an infamous alchemist and gains the nickname Fullmetal, the boys' journey embroils them in a growing conspiracy that threatens the fate of the world.

Still threatened by the Titans that rob them of their freedom, mankind remains caged inside the two remaining walls. Efforts to eradicate these monsters continue; however, threats arise not only from the Titans beyond the walls, but from the humans within them as well. After being rescued from the Colossal and Armored Titans, Eren Yaeger devotes himself to improving his Titan form. Krista Lenz struggles to accept the loss of her friend, Captain Levi chooses Eren and his friends to form his new personal squad, and Commander Erwin Smith recovers from his injuries. All seems well for the soldiers, until the government suddenly demands custody of Eren and Krista. The Survey Corps' recent successes have drawn attention, and a familiar face from Levi's past is sent to collect the wanted soldiers. Sought after by the government, Levi and his new squad must evade their adversaries in hopes of keeping Eren and Krista safe. Eren and his fellow soldiers are not only fighting for their survival against the terrifying Titans, but also against the terror of a far more conniving foe: their fellow humans.

Seeking to restore humanity's diminishing hope, the Survey Corps embark on a mission to retake Wall Maria, where the battle against the merciless Titans takes the stage once again. Returning to the tattered Shiganshina District that was once his home, Eren Yeager and the Corps find the town oddly unoccupied by Titans. Even after the outer gate is plugged, they strangely encounter no opposition. The mission progresses smoothly until Armin Arlert, highly suspicious of the enemy's absence, discovers distressing signs of a potential scheme against them. Shingeki no Kyojin Season 3 Part 2 follows Eren as he vows to take back everything that was once his. Alongside him, the Survey Corps strive—through countless sacrifices—to carve a path towards victory and uncover the secrets locked away in the Yeager family's basement.