Magnum is to spend a week aboard a luxury cruise ship guarding an Amakua, a valuable wooden Hawaiian statuette recently purchased by Robin Masters, to be displayed on the liner while en route to the Hilo Museum. But Thomas and Higgins find that Apollo has been shot and seriously wounded after thieves attempted to steal the artefact from the Estate. Expecting the would-be robbers to try again during the cruise, Thomas secures Rick and T.C.'s additional help in guarding the artefact, but they find themselves on-board with a ship load of suspects, all potential thieves of the Amakua...