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 Magnum 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 situation 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.

When Higgins unwittingly causes Magnum to wipe an expensive computer game loaned from T.C., and Thomas accidentally erases a chunk of Higgins' memoirs stored on the computer, a feud breaks out between the pair. Magnum is trying to break a major, crooked gambling ring that is operating on the islands, but it is none too easy while in the middle of the falling out with Higgins, which starts out with each trying to out-do the other with "eye for an eye" practical jokes, and quickly develops into a particularly bitter battle of wills.