The movie opens with a group of medical researchers conducting an experiment to revive a dead pig using a serum called "Lazarus." The team, led by Frank and his fiancée Zoe, discovers the serum can potentially bring the dead back to life. After successfully reviving a deceased dog, they face strange changes in its behavior.

The story escalates when Zoe is accidentally electrocuted, leading Frank to use the serum on her to bring her back. Upon revival, Zoe exhibits heightened brain activity and develops telekinetic and telepathic powers, but she also begins to exhibit increasingly erratic and dangerous behavior.

As Zoe's transformation progresses, the team becomes wary of her new abilities. Niko is killed by Zoe in a fit of rage, followed by Clay, and Frank realizes the extent of Zoe's transformation into something sinister. In a final confrontation, Frank attempts to kill Zoe, but she overpowers him.

Eva, the team's videographer, tries to stop Zoe and finds herself transported into Zoe's traumatic memories of a fire she accidentally caused as a child. In a climactic moment, Eva injects Zoe with a lethal syringe, seemingly killing her. However, in a shocking twist, Zoe reappears disguised as a fireman and kills Eva. The film concludes with Zoe reviving Frank, leaving their fates ambiguous.