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.

A friend of Magnum's from his Navy days, "Hot" Rod Crysler, is being blackmailed by a corrupt narcotics officer into delivering marijuana.