Private eye Philip Marlowe investigates a society girl's involvement in the murder of a pornographer.

Los Angeles private detective Philip Marlowe is summoned to the mansion of General Sternwood, a wealthy, aging invalid with two wild young daughters: the predatory, childish Carmen and the divorced Vivian Rutledge. Sternwood explains that Arthur Gwynne Geiger, a rare book dealer, is demanding payment of Carmen's gambling debts. Sternwood adds that earlier, a man named Joe Brody made a similar request, which was handled by ex-bootlegger Sean Regan, who has since disappeared. Although Marlowe advises Sternwood to pay the money, he agrees to look into the matter for him. After he leaves the general, Vivian asks to speak with him. She assumes that Sternwood hired Marlowe to look into Regan's disappearance, but Marlowe reveals nothing. At Geiger's store, Marlowe questions Agnes, the attendant, about rare books, and her confused response convinces him that the store is a cover for some illegal activity. The attractive bookseller across the street confirms his guess, and Marlowe waits at her shop for Geiger to make an appearance. Marlowe follows Geiger to his house, where, after a while, Carmen arrives. Later, Marlowe hears a scream followed by gunshots. Inside the house, Marlowe discovers a drugged Carmen with Geiger's dead body. Marlowe also finds a hidden camera with no film in it and a book containing the names of Geiger's blackmail victims. After Marlowe drives Carmen home, he returns to Geiger's, but in the meantime, the body has been removed. Later, one of Sternwood's cars containing the body of his chauffeur, Owen Taylor, is dredged out of the ocean. That afternoon, Vivian tells Marlowe that blackmailers have demanded $5,000 for a compromising photograph of Carmen taken at Geiger's the previous night. When Marlowe asks if she can pay the money, Vivian says she might be able to get it from Eddie Mars, the gambler whose wife ran off with Regan. Marlowe then returns to Geiger's store, where he sees two men loading Geiger's stock into their car and tails them to Brody's apartment. Later, he learns that Mars owns the house where Geiger was shot. That evening, when Vivian reports that the blackmailers failed to contact her, a skeptical Marlowe drives to Brody's apartment building. Vivian and Agnes are both hiding inside, and Carmen arrives later, intending to shoot Brody. After Marlowe disarms Carmen, Brody admits that he is the blackmailer, but denies that he killed Geiger. Marlowe forces Brody to give the photographic negative to Vivian, who then takes Carmen home. Marlowe explains that Taylor, who was in love with Carmen, shot Geiger and then accuses Brody of killing Taylor. Brody is about to tell Marlowe what information Geiger had on the Sternwoods, when he responds to a knock on the door and is shot. Marlowe catches the killer, Geiger's assistant Carol Lundgren, who believed that Brody murdered Geiger and shot him in retaliation. Now that the murders seem to be solved, Vivian tries to dismiss Marlowe, but he is convinced that Mars knows something about Regan's disappearance. Marlowe's suspicions of Mars increase when Vivian wins a lot of money gambling at Mars's club, only to have it stolen later in what appears to Marlowe to be a phony holdup. When Vivian later tells him that Regan has been found in Mexico, Marlowe believes that she is trying to throw him off Regan's trail. Subsquently, Marlowe learns from Agnes the whereabouts of Mars's wife Mona, who was supposed to have run off with Regan, and drives to the hideout, where he is taken prisoner by Mars's men. Vivian is also hiding out at the house and with her help, Marlowe shoots Mars's hired killer Canino, and they make their escape. Marlowe then lures Mars to Geiger's house and accuses him of blackmailing Vivian to keep Carmen's murder of Regan secret. After Mars is mistakenly killed by his own men, Marlowe tells the police that Mars murdered Regan and privately exacts Vivian's promise that she will send Carmen away where she will be prevented from hurting anyone else.