A spore is discovered that can reanimate dead cells and cause zombie-like effects in humans. Small doses cause psychoactive effects but larger doses deteriorate mental faculties and cause cannibalistic, zombie-like behavior. An overdose kills the host but resurrects them as a zombie. The spore spreads globally, leading to a zombie apocalypse as the reanimated corpses cannot be killed through conventional means and only destroyed by dismantling the entire body.