Magnum is working on a case when he sees a young native Hawaiian girl become an accidental witness to a murder. With the gunman after her, Magnum saves the young woman as they escape by diving into the sea and is injured with a gunshot wound in the process. He regains consciousness several days later on the remote, secluded island of Kapu, after being rescued by a native fisherman from the island, and suffering from a hazy memory of the incident. There is no sign of the girl, and the island natives insist that he was the only one found. Thomas tries to remember the events that lead to him being on the island, but as he tries to uncover the secrets of the island and its people, it begins to seem more and more as if they don't want him to find any answers or to leave.

While Rick is planning a surprise birthday bash at the King Kamehameha Club for Icepick, Carol asks Magnum to observe a court case she is presenting before Judge Kearns, who drops the case on a simple technicality. She considers the Judge to be her mentor, but is concerned that of late he has been acting uncharacteristically, and suspects him of taking bribes to dismiss cases. She asks Thomas to help her hopefully disprove her worries. But the investigation turns up evidence that implicates Icepick, who in turn faces having to implicate the woman he was in love with decades earlier. Carol, Rick and Icepick must all face up to the weaknesses and mortality of their mentors.