Thirty-three-year-old narrator hero Philip Marlo, who had previously worked in the Los Angeles County Attorney's Office, has now become a private investigator and is investigating cases in which his clients are definitely not interested in publicizing them. He arrives at the home of millionaire Guy Sternwood, who tells Marlo that someone called Geiger is blackmailing his youngest daughter, Carmen. In addition, the husband of his eldest daughter, Red Regan, once an officer Ira, who took part in the Dublin uprising and then made good money by illegally selling alcohol in America during Prohibition, disappeared somewhere. Sternwood also reports that at one time, his daughter Carmen blackmailed a certain Joe Brody and he had to pay the latter five thousand dollars.
Marlo establishes an observation of the Geiger bookstore and concludes that the sale of second-hand and rare books is only a roof for the sale of products of a clearly pornographic nature. In the evening, Marlo begins to observe the house of Geiger, who discovers a car belonging to Carmen. Soon shots rang out in the house. Penetrating inside, Marlo discovers the owner’s corpse and completely naked Carmen in a state of drug intoxication. Apparently, she posed in front of the owner's camera.
Having hurriedly delivered the girl to her father’s house, Marlo again returns to the Geiger house, but the owner’s corpse mysteriously disappears. The next morning, Marlo learns that the Sternwood “Buick” was found in the sea at the pier, and in it is the corpse of a man who worked with the Sternwoods as a driver and, apparently, was in love with Carmen.
Resuming monitoring of the Geiger bookstore, Marlowe discovers that the pornographic product is urgently transported to the apartment to the very Brody that Sternwood mentioned earlier. Returning home, he finds his elder sister Carmen Vivien. She is trying to understand why Marlo was visiting their house the day before, and in addition, reports that she was sent photos of Carmen naked and demand five thousand dollars for negativity and prints. In principle, she is ready to get money - for example, from the owner of the Cypress casino, Eddie Mars, with his wife, according to rumors, Red Regan fled.
Marlo goes to Brody. There is also a blonde who worked in a Geiger store. Marlo says that he knows everything about Geiger’s business, and talks about the role that Brody played there, as well as about what Carmen showed on Brody as a Geiger killer. In the midst of negotiations, Carmen appears and tries to shoot Brody. She threatens to tell the truth about Geiger’s death and demands a photograph. She grabs a revolver and shoots at Brody, but misses. She manages to persuade her to go home, and Marlo gets the photos. Cornered Brody admits that he took them from Taylor, whom he tracked down at Geiger’s house. He caught up with him in a secluded place and, stunned, took away the very photographs that he had taken from Geiger, having shot him beforehand.
Clarification of the relationship was interrupted by a new doorbell, and Brody, who came out to open, was mortally wounded by an unknown visitor. Marlo soon goes on his trail. This is a certain Lindgren, who worked in a Geiger store and connected with him by homosexual relations. Lindgren shot Brody, because he was sure that it was Brody who killed his friend. Marlo brings him to Geiger’s house, and he shows where the corpse is. As for Taylor, by shooting Geiger in front of Carmen, so beloved by him, and then losing his compromising photographs after a collision with Brody, he committed suicide by directing the car into the sea from the pier.
formally, Marlo fulfilled the order of his client and dealt with those who blackmailed him, but professional excitement makes him try to find out what happened to Rygan Rygan. Eddie Mars, who did not show much interest in the police investigation into the disappearance of Regan and his wife, categorically denies any involvement in this case. He assures Marlo that he did not kill Regan, and he is inclined to believe him.
Returning to his home, Marlo finds in his bed completely naked Carmen. With great difficulty, he manages to expose this sex-obsessed person outside the door. The next day, Marlo draws attention to the fact that he is "grazed" by a man in a gray "Plymouth." It turns out that someone Harry Jones is ready for two hundred dollars to tell him some confidential data. He knows where Eddie Mars’s wife is currently hiding. According to him, she is in a secluded place forty miles from Los Angeles since Red Regan disappeared.
Marlo is willing to pay for the information and promises to bring the money in the evening at the address provided by Jones. Upon receiving the fee, Jones promises to take Marlo to the very Agnes who worked with Brody, and there already give him the exact address of Mona Mars. However, having appeared at the indicated time at the indicated place, Marlo discovers that Jones already has a guest. It turns out to be a certain Canino, whom Eddie Mars occasionally uses as a killer. Both of them were seriously frightened by the contact of Jones and Marlowe. Canino digs out Jones' address for Jones, then treats him to a drink with potassium cyanide and sets off to deal with Agnes.
Marlo manages to get ahead of Canino. He meets with Agnes, and she, having received the required amount, informs him of the whereabouts of Mona Mars. Marlo goes to where the wife of Mars and the mistress of Red Regan are hiding. Canino meets him. When Marlowe comes to, he finds out that he is firmly attached to the sofa, and in his hands he also has handcuffs. With him in the room is the blonde, the very Mona Mars that interested him. She assures Marlowe that Eddie has nothing to do with the disappearance of Red Regan, and then unties him and asks him to leave as soon as possible. But Marlo does not go far — to his car, which he left on the highway, picks up a revolver from there and returns back. He has no doubt that Canino will return only to kill him and his boss’s wife.
The Marlo maneuver brings success. He manages to lure Canino out of the house and shoot him, despite the handcuffs.
Marlo visits old Sternwood again. He reproaches him for his initiative: after all, Marlo’s task was only to deal with the blackmailer, and not to search for the missing Regan. He, however, with his inherent bluntness, declares that he knows better how to protect the interests of the client, and Geiger was just a small bipod, probing Sternwood for vulnerability. According to Marlowe’s calculations, it was Regan that was the weak spot, and Sternwood was not worried about money or his spoiled daughters. He simply did not want to be deceived by a man who caused him sincere sympathy.
After hearing this tirade, Sternwood instructs Marlowe to continue the investigation. But Marlo is already close to a solution. He encounters Carmen, who asks to teach her to shoot. He agrees, but only where they are not heard. He takes her to a secluded place of her choice, hands her a revolver and goes to set a target for shooting. Then she opens fire on him, and if Marlo had not prudently loaded the revolver with blank cartridges, he would not have finished the investigation.
Having shot all the cartridges, Carmen falls in a severe fit, and Marlo takes her home. There he meets Vivienne and tells her about the results of his experiment. Geiger blackmailed the general on the instructions of Mars. And if he agreed to pay, Eddie would have pumped a lot of money out of him, because he knew what happened to Red Rygan. He was killed by Carmen Sternwood - apparently, in revenge for the fact that he rejected her sexual harassment. Vivien, however, does not intend to lock herself. She admits that she learned about Carmen’s act and asked Mars to help hush up the case. She had no doubt that at the first interrogation, the weak-witted Carmen could not stand it and admitted, and that would kill her father. Vivien understood that Eddie Mars wouldn’t leave her so easily, but she didn’t see any other way. She waits anxiously at what price Marlo will ask for silence. But he is not going to cash in on his gloomy discovery. He only demands that Vivien find a reliable psychiatric hospital for her sister, and he will deal with Eddie Mars himself and make sure that he no longer bothers the Sternwoods.
