In a world where humanity survives behind massive concentric walls, colossal humanoid Titans of unknown origin periodically breach the defenses and devour people. Eren Yeager witnesses his mother's death during a catastrophic wall breach and vows to eradicate every Titan. He joins the Survey Corps, an elite military unit dedicated to exploring beyond the walls and understanding the Titans' origins. Alongside his childhood friends Mikasa and Armin, Eren discovers he possesses a shocking ability: he can transform into a Titan himself. As the trio uncovers dark secrets about the walls, the Titans, and their own world's history, they confront increasingly complex moral questions about freedom, determinism, and the true nature of their enemies. The series escalates from survival horror into a sprawling political and philosophical thriller, revealing that the conflict extends far beyond simple monster-hunting into questions of identity, power, and what it truly means to be human.