At the urging of the students in the private investigation class that Magnum is teaching at a local college, he takes on the investigation into the disappearance of a student's fiancee as the class' field work.

Robin and Higgins simultaneously ask Magnum to do some investigative work, so Thomas calls on St. Louis-based gumshoe Luther H. Gillis to nail the man who's blackmailing Higgins, while Thomas goes undercover to investigate embezzlement in a bank owned by Robin's friend.