The Titans have been eradicated, but an unknown strain of sickness has begun vastly spreading throughout the civilians of Paradis, turning them into mindless undead versions of themselves. Zombies are created by this said sickness, which causes a mutation in the human brain and reanimates anyone who has passed away, even if they were uninfected on the surface. Though they are seemingly alive, they cannot speak nor perceive emotions, and their only goal is to eat human flesh.