Joe Mannix is a Los Angeles-based detective who ends up taking a lot of punishment. When the show starts, he works for a large L.A. detective agency, Intertect. But beginning in season two, he sets out on his own and becomes a private investigator, assisted by loyal secretary Peggy Fair, the widow of a police officer. In the course of solving crimes, he can be expected to be shot, beaten, knocked unconscious, driven off the road or similarly injured. But despite all the bodily trauma, Mannix always gets his man.