It is almost the 4th of July, and Higgins heads to Maui for an annual writers conference, and Rick and T.C. take a trip away, leaving Thomas on the Estate to face the horror of his tax audit. But that's nothing compared to the terror yet to come when Magnum becomes the focus of a crazed, obsessed killer, who repeatedly phones him with cryptic nursery rhyme riddles of upcoming killings. At first he thinks it is a crank caller, but the full reality of the sitution hits home when a prostitute is murdered in circumstances reflecting the clues given, and the menacing calls continue, with the deranged killer boasting about his crimes and giving clues of the next one...

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.

Lieutenant Tanaka is murdered while working undercover. The official Police report states that Tanaka died in a car accident, but Thomas believes that something is being covered up, and sets about trying to answer the many questions about his friend Tanaka's death, uncovering switched identities and drug-running in the process...

Thomas ponders his future while paying a visit to his family in Virginia, where he unexpectedly meets his grandfather and considers an offer to be reinstated to the Navy; Thomas returns to Hawaii to ascertain whether former girlfriend Linda Lee Ellison is being stalked; Rick prepares for his wedding to Cleo; Thomas and Linda renew their relationship as he searches for her stalker; Thomas becomes increasingly certain that his daughter Lily may still be alive.

As Rick's wedding looms ever closer, Thomas continues surveillance on Linda to catch the psychopathic killer who is stalking her; T.C. faces a reconciliation with his estranged wife; Thomas gets surprising news about his theory that Higgins is really Robin Masters, as well as the true fate of Lily.