While Higgins is preparing to direct a selection of pieces from Gilbert and Sullivan's comic opera The Mikado, to be staged at the Estate, Magnum is hired by an attractive young woman to find her missing brother, whom she claims has disappeared after joining a religious cult. The girl has musical experience and agrees to help out with rehearsals of Higgins' production while Magnum seeks out her missing brother.

A high-speed car chase between Magnum and some black-market operatives spins wildly out of control when a young woman gets caught in the crossfire. But when he continues to have run-ins with the devious thugs, he begins to wonder if this "innocent victim" might be more than she seems.