Zach Orfman hermano is deeply shaken when his girlfriend, Beth Slocum, tragically dies after being bitten by a venomous snake during a hike. As he struggles to cope with his grief, Zach begins spending more time with Beth's parents, [Geenie] and Maury Slocum, seeking some form of comfort and understanding. During their conversations, Zach confesses that he and Beth were experiencing difficulties in their relationship, but [Maury] urges him not to let these problems define who they are or their future together, offering a bit of reassurance amidst the chaos.
However, Zach's concerns intensify when the Slocums suddenly cease all contact. Driven by desperation, he visits their home and catches a glimpse of Beth through a window. Despite his calls to be let in, he is turned away by his brother Kyle, a security officer. Zach's insistence that Beth is still alive worries his parents, causing tension at home. That night, Zach, overwhelmed with doubt, breaks into the house and discovers that Beth's parents have been hiding her alive all along. This revelation sparks a heated argument, after which Zach storms off in frustration. Later, he visits Beth's gravesite and finds a large hole in her burial spot — a sign that Beth has reappeared. He confronts her parents, who reluctantly admit that Beth seemingly came back from the dead after her funeral, appearing healthy and whole. Notably, they are hesitant to tell Beth that she died, and they keep her sheltered during the day.
When Zach takes Beth out for a daytime outing in the park, her face suddenly begins blistering, an indication that something is terribly wrong. Despite Maury forbidding Zach from seeing Beth, Zach keeps sneaking around to be with her. Beth's behavior becomes increasingly erratic and violent, marked by severe mood swings. Zach notices that other people in town are acting strangely — gaining strength and exhibiting violent tendencies similar to Beth. His suspicions grow when he visits a diner and runs into his childhood friend, Erica Wexler, who offers her condolences. As they leave, tragedy strikes when Zach accidentally runs Beth over with his car. The scene escalates as Beth frightens away bystanders with her screams, showing she has become unpredictable and dangerous.
In a tense moment, a clash with Erica occurs when Beth mistakenly accuses Zach of cheating, leading to further chaos. Zach takes her to her grave, where he finally tells her the truth about her death. He attempts to break off their relationship, but Beth becomes furious and drives off in his vehicle. Returning home, Zach is shocked to discover that his late grandfather appears to have returned as well, adding to the unsettling atmosphere.
With Maury's help, Zach is pressured into telling Beth the full truth and promising to stay with her forever — a compromise that Zach is reluctant to make. As Zach drives away with the increasingly distraught Beth, Maury intervenes, knocking Zach unconscious and taking her back home. When Zach wakes up, he finds his house turned upside down: a stranger is inside, and the backyard contains burnt bodies he believes to be his family.
Faced with despair, Zach considers leaving town but then changes his mind. He heads back to the Slocum residence where he discovers a horrifying sight: Beth, now fully transformed into a bloodthirsty zombie, has already eaten Maury and some of Geenie’s fingers. Despite the nightmare, Zach manages to let Geenie escape and calms Beth temporarily by promising to hike with her. Along the way, they encounter Kyle, who is hunting zombies, and he hands Zach a handgun, urging him to put Beth out of her misery.
At a cliffside, Zach and Beth share a heartfelt, tearful farewell. Zach apologizes for not fulfilling her desires when she was alive. They declare their love for each other before Zach gently shoots Beth in the head, ending her suffering. The story concludes with Zach reuniting with his family at a safehouse, where a traumatized Erica, who earlier had to kill her own grandmother, is also present. The survivors plan to leave town now that things seem to have returned to normal, as indicated by a TV report announcing the end of the chaos. Sometime later, Zach visits Beth and Maury’s graves, leaving a scarf on Beth’s tombstone and a chess piece on Maury’s as tokens of remembrance. As Zach’s mother picks him up, he invites Erica to dinner. She accepts, smiling as they drive off into an uncertain future, still haunted but hopeful amid the aftermath of the terrifying events.
