Master raconteur Crisp tells another of his South Sea adventures with enough undersea world (or sea underworld) terror and mystery to satisfy the most avid. Nick Masters is youngest of the crew on the salvage ship Hukapuka, whose captain, on the trail of treasure now, leads them to sinister Chaplulu Bay in the Maccassar Straights. Excitement there culminates in the discovery that one of their own crew is after the treasure too, and that the treasure is the culprit's ""take"" during a former stint as a gun runner. Sure plot development sustaine suspense. Richard Powers' drawings carry out atmosphere.