In 1989, we meet Lisa Swallows, a troubled teenage girl grappling with the profound grief of losing her mother, who was tragically slain by an axe murderer two years prior. Her situation is further complicated when her father, Dale (Joe Chrest), marries Janet (Carla Gugino), a self-absorbed and cruel woman. This new union brings Lisa a vivacious and popular stepsister, Taffy (Liza Soberano), but it does little to alleviate her feelings of isolation. Much to her family's dismay, Lisa frequently finds solace in the eerie quiet of the Bachelor's Grove Cemetery, where her heart finds a haunting place of peace.
After a grim incident involving a tanning bed, which results in Lisa's near-electrocution, she and Taffy go to a party where Lisa becomes unwittingly drugged and is almost sexually assaulted by the classmate Doug (Bryce Romero). In an emotional frenzy, Lisa seeks out the cemetery once again, speaking to the grave of a young Victorian man who perished in 1837. She wishes to be united with him, unaware that her sadness awakens his spirit. His life had unfolded in another era, filled with love and tragedy, ultimately ending in a lightning strike that left him to rest in the graveyard. Following Lisa's heartfelt confession, a bolt of mysterious green lightning resurrects him as the Creature (Cole Sprouse), a lovesick zombie seeking connection.
As Lisa navigates the complexities of her new family life, tension builds when Janet confronts her over a broken mirror. An unexpected intrusion occurs as the Creature enters her home, and after a moment of fear, Lisa recognizes him as the young man from her fantasies. Hiding him in her bedroom closet, she begins to bond with his broken, dirt-covered form. Fearing that she might be labeled mentally unstable, Lisa fabricates a story about a burglar to cover the mess left behind by the Creature. However, Janet's dismissal of her concerns escalates when the Creature retaliates against her cruelty, culminating in Janet’s violent death when he cuts off her left ear, which Lisa, in a tragic gesture of loyalty, sews onto his head.
Combining their efforts, they dispose of Janet's body in the cemetery, and Lisa experiments with reattachment using the tanning bed, finding new ways to revitalizes the Creature. Things take a darker turn when she lures Doug to the graveyard, resulting in the Creature killing him to further restore his former self. As these horrific events unfold, the police start investigating the strange disappearances, while Taffy, unaware of Lisa's true involvement, mourns.
Meanwhile, Lisa’s affection for Michael (Henry Eikenberry) takes a devastating blow as she finds him with Taffy, leading to an explosive confrontation with the Creature, who viciously exacts vengeance. In a poignant moment before confronting the Creature again, she gifts Taffy her late mother's rosary, reinforcing their bond amid the chaos.
In a shocking climax, Lisa chooses to embrace death alongside the Creature, fully aware of the darkness that envelops their love. She convinces him to use the tanning bed again, culminating in a tragic but liberating act as she burns to death.
Months later, Dale and Taffy find themselves mourning at the graves of Lisa and Janet. Meanwhile, the Creature, now fully alive and articulate, sits comfortably on a park bench, reading poetry to a bandaged and resurrected Lisa, symbolizing the bizarre yet profound nature of their twisted love story. > "I’ll always be with you," he whispers softly as she rests her head on his lap.
