A mystery film is a film that revolves around the solution of a problem or a crime. It focuses on the efforts of the detective, private investigator or amateur sleuth to solve the mysterious circumstances of an issue by means of clues, investigation, and clever deduction. Mystery films include, but are not limited to, films in the genre of detective fiction.
While cinema featured characters such as Sherlock Holmes in the early 1900s, several other Sherlock Holmes likes characters appeared such as Boston Blackie and The Lone Wolf. Several series of mystery films started in the 1930s with major studios featuring detectives like Nick and Nora Charles, Perry Mason, Nancy Drew and Charlie Chan. While original mystery film series were based on novels, by the 1940s many were sourced from comics and radio series. Towards the 1940s these series were predominantly produced as b-movies, with nearly no mystery series being developed by the 1950s.