The mystery genre includes stories that revolve around a crime and the adventures of a protagonist as he or she tries to find the perpetrator of the crime. The genre has long been widespread in popular fiction and on the radio, and with the introduction of television, the mystery genre was quickly and successfully translated to the medium. TV mysteries are typically a subgenre of the crime genre. Mysteries may also be related to the horror and suspense genres.
The defining characteristic of a mystery story is a crime or, less commonly, some other type of puzzle with a hidden answer. Almost always the answer to the puzzle-the person who committed the crime-is unknown to the audience until the end of the story, when the protagonist finally solves the mystery, allowing the viewer to try to solve the crime along with the character in the story. In some cases, the viewer may be given the answer to the puzzle while the hero remains in the dark.
The detective story is a common type of mystery. In these stories, a police detective or sometimes a team of detectives tries to solve the crime, which is very often a murder. The heroes are not always police officers, however; private investigators are common protagonists, and the adventures of amateur sleuths are also popular. In stories involving amateur detectives, the heroes are often drawn into the mystery by chance, and they are reluctant and sometimes bumbling in their quest to figure out the puzzle.
True-crime documentaries, in which the circumstances of a non-fictional crime are considered, are sometimes structured to mimic the fictional mystery forms. In these programs, the details of the real-life crime are revealed incrementally and in a manner meant to develop suspense and keep the viewer guessing until the end.