In a dark and unsettling morgue, BJ finds himself in a disturbing situation when he becomes intimate with a corpse marked by a bio-hazard symbol on its toe tag. Following this bizarre incident, he mindlessly cleans himself while clutching a barren test tube. Amidst the chaos, Samantha is trying desperately to move on from her breakup with her girlfriend, Nikki, at a lively house party. The enthusiastic host, Alice, provides her with strong cocktails, and Zain offers her illicit substances to dull the pain. As the night descends into a haze of intoxication, BJ approaches Samantha with another drink. Despite her insistence on being a lesbian, she succumbs to her inebriation and BJ takes advantage of her vulnerability.
When the morning light breaks, Samantha mistakes her ordeal for merely a terrible hangover. As she engages in a tense exchange with her mother—who grapples with accepting Samantha's sexuality and fears for her potential drug relapse—the troubling news begins to unfold. Alice shares that the police are on the lookout for BJ, whom she doesn’t know personally.
At her workplace, Samantha struggles with the simplest tasks, overwhelmed by noise and battling significant physical discomfort. After experiencing a heavy menstrual flow, she consults her doctor. Despite her claims of never having been with a man for nearly a year, he questions her based on the rash he discovers, raising concerns about a sexually transmitted disease.
As her symptoms worsen and her health degenerates, Samantha attempts to mend her fractured relationship with Nikki, who is dismissive and hurtful, revealing that she never informed Samantha about a scholarship offer. Meanwhile, Samantha's physical condition deteriorates further—her eyes become bloodshot, her hair begins to fall out, and during an emergency shift at the restaurant, her nails peel away. Frightened, she seeks out her doctor again, who instructs her to remain isolated until further tests clarify her mysterious affliction. Ignoring the advice, she instead turns to Zain, who introduces her to heroin.
In a twist of fate, Alice urges Samantha to report her assault to the police, but Samantha, feeling betrayed, lashes out and storms away, unaware that Zain has already exposed his dealings with BJ to Alice. Back at home, a heated argument with her mother leads to Samantha's emotional collapse. Determined to compete in a flower show, she faces rejection due to her disheveled appearance and the unhealthy state of her plants.
Desperate for comfort, she turns to Nikki once more, only to face cold rejection as Nikki accuses her of being confused about her sexuality. Enraged and desperate, Samantha responds in violence, choking Nikki to death in a fit of rage. Consumed by her descent into madness, she then makes her way to Alice’s house, culminating in a gruesome act where she murders Alice, ripping out her throat.
Trying to mask her madness, Samantha invites Riley, who has secret feelings for her, to Alice's home, but her grotesque transformation backfires as maggots spill from her body, horrifying him. As the situation spirals out of control, he finds Alice's lifeless body and Samantha flees the scene.
While driving in a daze, she loses consciousness, leading to a catastrophic crash. Upon emerging from the wreckage, Samantha is no longer the woman she once was; she has succumbed entirely to the horrors of her own making, transformed into a horrifying zombie. As her mother arrives, pleading with the police to spare her daughter, the officers warn Samantha against any sudden movements. In a terrifying moment, she lunges at her mother, a haunting echo of her tragic descent into madness.
