Simon McNally, the main character, suffers from paranoid schizophrenia and experiences vivid hallucinations, including hearing the disembodied voice of his abusive, deceased father who belittles him. His mental illness has severely impacted his ability to function in daily life and maintain employment, leading to a decade-long hospitalization and dependence on his sister for support.

Initially skeptical and reluctant, Ed Deerman, a retired campus security guard, agrees to help Simon investigate the alleged kidnapping Simon witnessed. Despite doubts about Simon's reliability due to his mental illness, Ed gradually becomes a supportive ally. Their partnership evolves from mistrust to friendship, culminating in Ed taking pity on Simon and rejoining him in the search, and later standing by him during dangerous confrontations.

Simon and Ed encounter several challenges: the police dismiss Simon's claims as delusions; Ed's attempt to obtain information from the DMV is refused, leading to Simon's violent outburst; questioning local sex workers results in Ed's car being vandalized by their pimp; and they face threats from the kidnappers, including an attempt on Ed's life by one of the perpetrators.

Simon struggles to distinguish between hallucinations and reality due to his schizophrenia. He is haunted by his father's voice telling him he is hallucinating and too weak to help. However, the film reveals that Simon's witnessing of the kidnapping is real, challenging both the characters' and audience's doubts about his reliability and highlighting his courage despite his mental health struggles.

By the film's end, Simon's brave actions lead to the rescue of the kidnapped woman and the capture or death of the perpetrators. Although he unintentionally kills one intruder and is arrested, he is likely to face minimal charges due to self-defense. Importantly, Simon gains validation and appreciation from Ed, Detective Glover, and the rescued woman, which contributes to his emotional healing and sense of being understood.