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...