One day the dive instructor Fred Norman, who works at a jet-set resort on the Costa Smeralda, is approached by Andrea Jacobs. She is the girl-friend of the gangster Harry Lang. Some years ago, both have the cash of a transport robbery sink into the sea, to secure this stolen money for their fellow gangsters. Jacobs and Lang force Norman to assist them to appear the gold. There is tension on board of the fishing cutter, which attempts to discover the loot. Especially, when the operation appears to be much harder than expected. Furthermore, an ex-partner of both gangsters, Paul Barko, is trailing the trio.