As the soft-spoken Jim Tahna navigates his uneventful life as a security guard, he finds brief moments of peace during the solitude his job provides. However, this introverted individual harbors a deep-seated contempt for society and those who employ him. Outside of his nightly patrols, Jim engages in a rather unsettling hobby: dark tourism. His current obsession is with Carl Marznap, a notorious mass murderer and arsonist, whose twisted legacy he feels compelled to unravel by visiting the locations of his horrific crimes. Leaving the familiar streets of Yonkers, New York, Jim sets off towards California, where the malevolence associated with Marznap seems to permeate the air.
Upon his arrival, Jim's stark reality is abruptly altered with the introduction of Iris, a prostitute residing in the same run-down motel. His initial awkwardness during their interaction hints at a more profound discomfort, which he later articulates through voice-over narration—revealing a visceral loathing for individuals in her profession. A fortuitous encounter at a local diner with Betsy, a warm and welcoming waitress, takes a more positive turn. Adopting the guise of Carl, Jim concocts a heartbreaking story about his sister battling cancer, drawing Betsy into a bond forged in shared hardship. As their connection grows deeper, she invites him to attend an Alcoholics Anonymous meeting, potentially changing the course of their relationship.
As Jim further immerses himself in Marznap's twisted narrative, he begins to encounter intense hallucinations and fragmented memories that reflect the darkness simmering within him. In these moments, the ghost of Marznap visits him, encouraging Jim to expose the world to the sensation of being victimized. Marznap's dark history of abuse and neglect emerges, culminating in a vengeful desire against those he perceives as oppressors. This cathartic revelation serves as an ominous prelude to the chaos that is yet to come.
After the AA meeting, Jim and Betsy nurture their budding relationship, with Betsy inviting him for dinner at her home. As their bond deepens, she offers him marijuana, which he reluctantly accepts. The evening takes an unexpected turn when she attempts to kiss him; Jim's agitation and insistence on a non-sexual interaction leave Betsy feeling unsettled. Seized by a sudden fit of rage, he storms out, bewildering her.
With the ominous presence of Marznap continuing to haunt him, Jim is compelled to seek out Iris, the mysterious trans woman living in his motel. Their uncomfortable encounter climaxes in anal sex, triggering flashbacks to Jim's traumatic childhood experiences with a gang. The emotions that surface from these memories begin to consume him, reminding him of the deep-seated wounds he has long buried.
In a moment of candid sharing with Marznap, Jim divulges his belief that he is irrevocably broken. The following day, when Betsy attempts to reach out, he responds with a harsh retort, prompting her to leave in tears and leaving him in his isolation once again. His motel room becomes a refuge where he drowns in despair. In a shocking act of violence, Jim invades Iris's private space, chasing away her client before unleashing a brutal assault upon her. Following this explosion of rage, he berates not only Iris but also God and the very children who played a role in the trauma that has scarred him deeply. Emotionally exhausted, Jim drags Iris to a local church, where he chokes the life from her.
Soon after, he and Marznap plot their next steps together; Marznap advocates for self-destruction, a seduction that Jim ultimately cannot resist as he follows through with the fatal act of slashing his own throat. In a chilling conclusion, law enforcement uncovers that Jim's morbid fascination with dark tourism has resulted in six victims—each a trans woman involved in sex work. A young person, driven by their curiosity for the macabre, ventures into Jim's abandoned dwelling, only to come across a chilling message scrawled on the wall: "From this void, no one returns!"
