To smoke out the thief in a large family-owned business, Magnum feigns marriage to the CEO's niece, who drives a mean limousine and can't quite make up her mind how she feels about men, marriage, and Magnum.

When his lifeguard friend Marcus Phillips is found dead on the beach the day after he's seen sporting an expensive new car he can't afford, Magnum suspects foul play. A young woman with an ambition to rise in the ranks of the police department joins him in the investigation, and they uncover secrets at the center of Marcus' life which led to his death.