Michael and K. I. T. T. are about to test K. I. T. T.'s new function which should allow him to drive on water, but the test is aborted when K. I. T. T. detects an injured scuba-diver washed up on the shore. Befriending the young man's sister, Michael investigates just how the boy got wounded, and uncovers that he has been removing ancient Aztec treasure from a sunken galleon, falling foul of a determined treasure hunter...