In post World War IILos Angeles, Dix Steele is an ex-airman who roams the city at night. He offers to help a police detective friend, Brub, solve the case of a serial killer—risking revealing that he himself has strangled women on a monthly basis since arriving in LA. Eventually, actress Laurel Gray and Brub's wife Sylvia become suspicious of Dix and they aid the forces of justice to close in on the killer without him being aware of it.
Book to film
The film differs from the novel in several substantial ways. Mostly notably, in the film, despite being a violent man with a hot temper, Steele is innocent of the murder he's suspected of committing, and is sincere in his desire to be a successful screenwriter; in the novel, he is a misogynistic, sociopathic killer who claims to be a crime novel writer in order to sponge off of a wealthy uncle.[1][2]