Following the end of World War II, Cole Phelps, a decorated USMC veteran of the Pacific Campaign, returns to Los Angeles, California, to live with his family while taking on work as a Patrol Officer of the LAPD. After successfully solving a major murder case in 1947 and being promoted to detective, Phelps earns a reputation over the next six months for solving difficult cases for both Traffic and Homicide. Upon being promoted into Vice, he becomes involved in the investigation into morphine syrettes being sold on the street, stolen from the ship that had brought home his former Marine unit. During this time, he falls for German lounge singer Elsa Lichtmann, and soon has an affair with her. Phelps eventually learns that several members of his former unit stole and distributed the stolen morphine, only to be assassinated on the orders of Mickey Cohen, who controlled the drug trade and had resented the competition.