Private detective Philip Marlowe is hired by old General Sternwood to stop a blackmail attempt concerning his youngest daughter Carmen.
Marlowe tails the blackmailer called Geiger to his house at Laverne Terrace. Suddenly he hears a shot and sees some men rushing out to their cars. He breaks into the house, and finds Carmel drugged in a chair, with Geiger's dead body at her feet. An empty camera proves that a photo has been taken of her and the corpse, probably intended for further blackmailing.
A series of clues lead Marlowe to various persons involved in gambling. Wherever he finds them, he also finds Sternwood's oldest daughter, Vivian Rutledge, a divorced beauty. She and Marlowe fall in love with each other, although she continues double-crossing him. When Marlowe's investigations lead him to the casino owner Eddie Mars, the situation starts becoming very dangerous.
Everyone, including the district attorney, advises Marlowe to stop the investigation, but he is stubborn. Eddie Mars has a lot of henchmen, who do the dirty jobs for him, including murder. But Marlowe decides to set up a trap for Mars himself.
THE TELEGRAPH’S TIM ROBEY COLLIN SAYS: “The Big Sleep is the best scripted, best directed, best acted, and least comprehensible film noir ever made.”