Magnum's ex-wife Michelle. leaves her five-year-old daughter Lily to be safeguarded by Thomas, as she escapes Vietnamese assassins out to kill her and her husband, General Hue. As Thomas watches over the child, he begins to wonder why Michelle has suddenly left Lily with him and if Lily is his own daughter, and once again sets about trying to track down his elusive former wife.
- 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