The night of her birthday, L.A.
switchboard operator Norah Larkin opens the latest letter from her fiancé, a soldier serving in the
Korean War. The letter ends up revealing his plans to marry someone he met in Tokyo. Devastated, Norah accepts a date over the telephone with Harry Prebble, a
calendar girl artist. When she arrives at the Blue Gardenia, a
South Seas-themed restaurant, Prebble is surprised to see Norah rather than her roommate Crystal Carpenter. He plies her with several tropical cocktails until she is soused. He whisks Norah to his apartment to "show her his art". He puts on all his seduction moves, but Norah passes out on his couch. He awakens her and attempts a
date rape. She resists, striking him with a
fire poker and shattering a mirror. Semi-conscious, Norah flees, leaving her suede pumps behind. The next morning Norah is awakened by Crystal and discovers that she does not remember what happened the previous night. Meanwhile, police at a crime scene question Harry's maid. She admits to cleaning the poker and placing the shoes in the closet, ruining the crime scene. At the telephone office, police question women who posed for Harry's drawings. When Norah learns why, she seeks the nearest newspaper account of the slaying. It revives the vague flashback of wielding the poker and shattering a mirror. Popular columnist Casey Mayo dubs the presumed killer the "Blue Gardenia murderess" (a reference to the
Black Dahlia slaying). That night, Sally Ellis, Norah's other roommate, reads aloud the newspaper report that the suspect was wearing a taffeta dress. Frightened, Norah wraps hers in a newspaper and sneaks out in the wee hours to burn it in an outdoor incinerator. She is harried by a passing patrolman for burning after hours, but let off with a warning. To capitalize on the case's publicity, Casey writes a column calling for her to turn herself in to him rather than the police, promising fairer treatment. He receives several bogus calls from locals, but recognizes Norah's as genuine. He eventually meets her in his office. Norah tells him she is speaking for a friend, and Casey reveals that he is willing to pay for top legal representation if that friend agrees to surrender. The two later go to a diner, where Norah tells her supposed amnesiac friend's account of the murder which includes the detail of Prebble putting the Nat King Cole recording of
Blue Gardenia on the phonograph. Casey confirms the music by choosing it to play from the table-side
juke box. Casey asks to meet her friend at the diner the next day. Norah agrees, returns home and confesses to Crystal, who is sympathetic. The next day at the diner, Crystal meets Casey and points him to Norah's booth, where she drops her gambit. He feels shocked, because he had begun to fall in love with her. He also feels guilty, admitting to her that he was only pretending sympathy for the alleged killer when he thought it was someone else. The police later arrive on a tip from the counter man and arrest Norah. Confused, she leaves convinced that Casey double-crossed her. Leaving town, Casey notices that the music at the airport — the love theme from
Wagner's
Tristan und Isolde — is the same composition on the record that the maid found had been played on Prebble's phonograph. With the knowledge that the record found by the maid differed from Nora's account of the last music she heard in Prebble's apartment, Casey realizes the possibility that Norah is innocent. Following up his hunch, Casey and Police Captain Haynes go to the music shop that had its marketing identity on the record cover. The clerk says that Harry's ex-girlfriend Rose Miller sold him the record, and calls to her to come out front. Realizing the police are already upon her, she locks herself in the restroom and attempts suicide. From her hospital bed, Rose confesses. After Norah had passed out, Rose visited Harry's apartment distraught, and (implying she was pregnant) demanded that Harry marry her. He refused, and instead started playing the record that had brought them together,
Tristan und Isolde. Rose noticed Norah's handkerchief on the floor by the record player, and, jealous and enraged, she bludgeoned Harry with the poker. Cleared, Norah is freed and reveals that she has forgiven Casey and wants him. After learning that she is interested, Casey tosses his "little black book" to his buddy Al. ==Cast==