At a Los Angeles party, Harold “Harry” Lockhart recounts recent events. Fleeing a botched burglary in New York City, Harry’s friend is shot, forcing Harry to evade police by ducking into an audition. Harry unintentionally impresses Dabney Shaw with an outburst of remorse Dabney mistakes for method acting; Dabney takes Harry to Los Angeles to screen test for the role of a private investigator. At a Hollywood party, Harry meets “Gay” Perry van Shrike, an openly gay private investigator, hired to give Harry on-the-job experience for his role. Party host Harlan Dexter is a retired actor who recently resolved a feud over his wife’s inheritance with his long-lost daughter, Veronica. Harry also encounters his childhood crush Harmony Lane, but wakes up in bed with her hostile friend.
During a stakeout at a Big Bear Lake cabin, Perry and Harry witness a car being dumped in the lake and are spotted by two thugs. Perry realizes there’s someone in the trunk and shoots the lock in a rescue attempt, but accidentally hits the female corpse inside. They cannot report the body because it will appear Perry killed her.
Harmony contacts Harry, explaining that her sister Jenna came to Los Angeles, used Harmony’s credit cards, then supposedly killed herself. Believing Harry is a detective, Harmony asks him to investigate Jenna’s death. After Harmony leaves, Harry discovers the lake corpse in his bathroom. Harry and Perry dump the corpse, later identified as Veronica Dexter by police. Harry discovers it was Harmony’s credit card that was used to hire Perry to come to the lake, tying Jenna to their case. He goes to see Harmony, who accidentally slams the door on his finger, cutting it off.
At a party where Harmony is working, the thugs from the lake (Mr. Frying Pan and Mr. Fire) beat Harry and order him to cease the investigation. While taking Harry to the hospital, Harmony sees the thugs heading to Perry’s latest stakeout. Realizing that Perry is heading into a trap, she leaves Harry in her car and runs off to warn Perry, with Frying Pan being killed by an armed food-cart operator. A pink-haired girl, affiliated with the thugs, steals Harmony’s car and unwittingly drives an unconscious (on pain-killers) Harry to her house. Mr. Fire arrives and kills her; Harry recovers the gun and kills Mr. Fire.
Harmony meets Harry at his hotel where she reveals she had told Jenna, years ago, that Harlan Dexter was her real father, to hopefully diminish the pain of their sexually abusive father. They end up in bed, but just before anything can happen, Harmony reveals she had once slept with Harry’s best friend, and he throws her out.
After Harmony disappears following a lead, Harry and Perry investigate a private mental hospital owned by Harlan. Perry realizes Veronica was incarcerated there by Harlan so an impostor could end the inheritance feud. Harry unintentionally kills a murderous orderly, but they are captured by Harlan, who reveals that he plans to cremate his daughter’s corpse to remove any remaining evidence. Harry calls Harmony, who had not actually disappeared, but had simply gone to work. Harmony steals the van containing the corpse. Harry and Perry escape, but Harmony crashes the van. A shootout ensues, in which Perry and Harry are shot by the same bullet; Harry then manages to kill Dexter and his three thugs.
Waking in a hospital, Harry finds that Perry survived and Harmony is fine. Perry reveals that Jenna did commit suicide. Jenna had located Harlan, believing him to be her real father. She accidentally witnessed him having sex with Veronica’s impostor, Pink Hair Girl. Believing her new “father” was also incestuous, Jenna commissioned Perry to catch him in the act, then committed suicide.
Perry travels back to Harmony’s hometown and slaps around her father, who is now bed-ridden and helpless, belittling him for being a “big tough guy” when he abused the equally helpless Jenna.
Harry finishes his narration by stating that he is wrapping up the movie, now works for Perry, and thanks the viewers for watching.