Magnum marries the niece of the company president in order to catch a thief.
As part of his plan to catch the thief in a family-owned business, Magnum pretends he is married to the CEO's niece, who has unusual feelings about men, marriage, and Hawaii's most eligible P.I.
- 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
- Katherine Cannon as Marsha Mackenzie
- Nicolas Coster as Andrew "Andy" MacKenzie
- Mary Jackson as Grandmother MacKenzie
- Dick O'Neill as Harry MacKenzie
- Doreen McLean as Greta, Grandmother MacKenzie's Cook
- Kathy McCullen as Mary Jane Lodato, Magnum's Secretary
- Charles Peck as Otto, Grandmother MacKenzie's Butler
- Wayne Ward as Minister, at Wedding
- Katherine Cannon (Marsha Mackenzie) previously appeared in "Thank Heaven for Little Girls and Big Ones Too."
- At the honeymoon cottage, Magnum watches the original version of Gunga Din (1939).
- Higgins: My God, Rick, how can you drink that swill? Malaria-infested Burmese swamp water was more palatable.
- (to Rick)
- Higgins: Would you stop bobbing your head like some ludicrous car ornament and tell me who is responsible for these infractions.
- Marsha MacKenzie: What are you doing? WHAT are you doing!?
- Magnum: ... You kissed me.
- Marsha MacKenzie: (laughs) Oh, "I kissed you", that's typically male. Why would I want to kiss you??
- Magnum: I don't know, but it's nothing to get upset about.
- Marsha MacKenzie: Well, I guess I made a pretty rotten wife, huh?!
- Magnum: No, I didn't make such a hot husband...I guess this relationship stuff takes a lot of practice.
- Marsha MacKenzie: It's kinda like golf for me. No matter how hard I try practicing, I never seem to break a hundred. You know what I mean?
- Magnum: Yeah, I sure do.
- Marsha MacKenzie: Well...
- Magnum: Hey, we didn't do so bad after all. You know, all things considered.
- Marsha MacKenzie: Right, all things considered. (smiles)