Three demobilized United States Navy aviators, Johnny Morrison, Buzz Wanchek, and George Copeland, arrive in
Hollywood,
California. All three flew together in the same flight crew from
Kwajalein Atoll in the
South Pacific. Buzz has
shell shock and a metal plate in his head above his ear. While George and Buzz get an apartment together, Johnny surprises his wife, Helen, at her hotel bungalow where she is hosting a riotous party with many drunken revellers. Johnny discovers that Helen is having an affair with Eddie Harwood, the owner of the Blue Dahlia
nightclub on the
Sunset Strip. Johnny punches Eddie as he leaves and then apologizes for losing his temper. The party ends and everybody leaves. Helen, drunk, confesses to Johnny that their son, Dickie, who Johnny believed died of
diphtheria, actually died in a car crash that happened because she was driving while drunk. Johnny and Helen scuffle, which is witnessed by the hotel detective, "Dad" Newell. Johnny decides to leave. He pulls a gun on Helen, states 'that's what you deserve,' but drops the gun on a chair and leaves. Buzz goes out to find Johnny at his hotel bungalow. He meets Helen Morrison in the hotel bar and, unaware of her identity, goes to her bungalow for a drink to wait for Mrs Morrison. Helen rings Eddie who breaks up with her over the phone. However, she then blackmails him into seeing her again. Eddie visits Helen at her bungalow; this is witnessed by the hotel detective. Johnny is picked up by Joyce Harwood (who is driving to Malibu) while walking in the rain. She is estranged from Eddie. Neither reveals their names. Although attracted to each other, they part ways and Johnny spends the night in a beach-side inn. The next morning, at the same inn, Joyce sees Johnny at breakfast and reveals that she stayed at the same inn. They decide to walk on the beach to look for moonstones. Whilst purchasing a bus ticket for Los Angeles, Johnny hears the radio announce that Helen has been murdered and that Johnny is suspected. He then quickly leaves to board a bus. The police interview Newell, Harwood, Buzz, and George. Johnny checks in to a cheap hotel in Los Angeles under an assumed name. Corelli, the hotel manager, finds Johnny's framed photo of himself with Dickie and tries to blackmail him. Johnny punches Corelli out, smashing the frame in the process; he discovers on the back of the photo that Helen has written an insurance note revealing that Eddie is really Bauer, a murderer who is wanted in
New Jersey. Corelli revives and sells information on Johnny's identity to a gangster named Leo (the nightclub partner of Eddie), who then kidnaps Johnny when he visits George and Buzz. Buzz and George visit Eddie at the Blue Dahlia. Joyce, who has agreed to meet Eddie, introduces herself. As Joyce picks at a blue dahlia flower, the nightclub's music sets off a painful ring in Buzz's head. Lapsing into a fit, he remembers the agonizing music that he heard at Helen's bungalow, as she played with a blue dahlia. Johnny escapes Leo and his side-kick, knocking them both out just before Eddie arrives. They talk and Eddie admits with regret that, fifteen years earlier, he was involved in the shooting of a bank messenger. Leo comes around and tries to shoot Johnny, but during a scuffle, he shoots Eddie instead. Johnny ends up shooting Leo and flees to the Blue Dahlia, where the police are trying to force a confused Buzz to admit that he killed Helen. Johnny enters and suggests that Joyce turn up the jazz music that Buzz hates. As his head pounds, Buzz remembers leaving Helen alive in her bungalow. Newell tries to shift suspicion towards George, then attempts to leave as Police Captain Hendrickson confronts Newell with the accusation that he tried to blackmail Helen about her affair, and that he killed her when she refused to comply. Newell then tries to escape from the office but is shot dead by Hendrickson when he pulls his own gun. Later, outside the Blue Dahlia, Buzz and George decide to go for a drink, leaving Johnny and Joyce together. ==Cast==