It takes guts to challenge death. Vern Rigby, professional diver, beach-bum and ladies' man, was the best in the business until the day he helplessly watched while a tiger shark chewed his best friend to shreds. From the Red Sea to Singapore, the word went out: Rigby had lost his nerve. He'd joined the losers. Now there was a second chance-- a diving job on an old schooner chrtered by a pampered, pretty young couple and run by a crew of misfits--all of them hung up on a quarter of a million dollars' worth of sunken treasure. End-of-the-rainbow stuff? Sure it was. But what did he have to lose?