When he takes a job as a hotel detective, Magnum's attempts at catching a cat burglar preying upon guests are complicated by his relationship with a hooker who keeps getting him into trouble with both criminals and his boss.
- Tom Selleck as Thomas Sullivan Magnum IV
- John Hillerman as Jonathan Quayle Higgins III
- Roger E. Mosley as Theodore "T.C." Calvin
- Larry Manetti as Rick Wright