The novel begins when Miss Wonderly wants to hire the services of a private detective to find her missing sister, who happened to run off with a scoundrel named "Thursby". She offered a large sum of money to find him. Soon after the investigation began, one of the private detectives was shot and killed, followed by the murder of the man "Thursby". Spade realizes that he might be in hot water when the police begin to question if he was having an affair with the murdered man, his old business partner's wife. The police might think that he was the one who killed his