After her archaeologist father's boat is found deserted at sea in the Nehoa Channel, a young marine biologist student hires Magnum to find out what happened to him. Ancient superstitions say that the channel is ""cursed"", and local natives warn Magnum to stay away, but he is determined to get to the bottom of what happened to the missing man, and so, with aid of Rick's yaught, they go hunting for both sunken treasure, and whoever was behind the girl's father's disappearance...

Magnum is hired by an old friend's Japanese wife when her now wealthy husband is kidnapped and held for $500,000 ransom. She wants Thomas to deliver the ransom without her strict father, who has never approved of the marriage, finding out. But the further he gets involved, Thomas more and more comes to suspect that not all about the kidnapping is as it seems...