When Thomas's childhood friend and Naval comrade Dan Cook turns up dead, Thomas is adamant that the official cause of death, a burst bag of smuggled cocaine, is bogus, and enlists the aid of Dan's sister Alice in taking on the Navy to uncover the true nature of the top-secret assignment Dan was working on before his death.

For an upcoming charity auction organised by Higgins and an attractive socialite, to be held on the Estate, Robin Masters "donates" Magnum's services, to provide security over the valuable antiques up for auction at the event. Meanwhile, mainland Private Detective brothers A.J. and Rick Simon have been hired to steal back a Ki'i - a stolen Hawaiian artifact - by it's previous owner, who is in rapidly decreasing health and believes that he has been passed on a curse from which he will die, unless the Ki'i is returned to it's intended location of rest within the Hawaiian islands. But the "cursed" Ki'i seems to spell bad luck and trouble for all who come into possession of it...

The crossover continues on Simon & Simon S02E01 Emeralds Are Not a Girl's Best Friend (II).

Rick persuades Thomas to take a lucrative, straightforward missing-person case. But the client, a New York City cop, is secretly out to avenge his young granddaughter -- and he wants Magnum's help.

Thomas is running an errand to a local museum for Higgins' upcoming pageant for the Anglo-Hawaiian Historical Society, when he catches sight of a woman attending a funeral who, he soon learns, resembles a beautiful Hawaiian princess who tragically died in a fire in 1910. Thomas becomes enamoured with the elusive beauty, and experiences visions of himself, in 1900s naval uniform, with the woman. The mystery grows even more when he receives a package in the mail containing such a naval uniform, and a locket holding photographs of what looks like himself and the princess... Is Magnum once again experiencing something ethereal, or is somebody using the story of the princess to their advantage?...