The film was shot on location in Los Angeles, at LA Center Studios, and the Salton Sea.
While playing the trumpet in a burning room, the protagonist's voice is heard in narration. His story begins with him posing as "Danny Parker", a speed freak addicted to methamphetamine, who hangs out with friends while indulging in drugs. He also moonlights as an informant for two corrupt cops, Gus Morgan (Doug Hutchison) and Al Garcetti (Anthony LaPaglia). He is trying to set up a large meth score with notorious drug dealer Pooh Bear (D'Onofrio), an eccentric psychopath who lost his nose to excessive snorting of "Gak" (meth), while also attempting to set up a sting operation for Morgan and Garcetti.
When he returns home, Danny sheds his clothes and his personality, and basks in his past life as trumpet player "Tom Van Allen". He reveals to an abused neighbor named Colette (Deborah Kara Unger) that he was once happily married, only to watch as his wife was gunned down by masked thieves during a stopover at the Salton Sea.
When meeting with Pooh Bear, Danny becomes fearful of Pooh Bear's displays of bizarre homicidal behavior, so he tapes a gun to the bottom of a table.
Danny's parents-in-law track him down, believing he has sunk into depression after his wife's death, but he tells them he doesn't want their help. As the deal approaches, it becomes known that Danny is not only working for the police but FBI agents working to take down Morgan and Garcetti, who have committed multiple murders. It is also revealed that they were the men who killed his wife and wounded him as they robbed a drug dealer. Danny had started his own investigation when he found out who Morgan was and delved into the drug underworld to become a believable junkie.