An American gunrunner, Caine (Burt Reynolds) arrives in a small dusty town in Sudan after escaping corrupt government soldiers. Broke and desperate, he agrees to sign up as a deck hand to ichthyologist Dan Mallare (Barry Sullivan) and his mistress Anna (Silvia Pinal) who are supposedly collecting rare fish specimens. Caine soon discovers that his new employers are crooked treasure hunters looking for gold bullion buried in the deep, shark-infested waters and that they would stop at nothing to get their hands on sunken treasure. Arthur Kennedy co-stars as Doc, an alcoholic American doctor who befriends Caine. Co-written and directed by legendary director Samuel Fuller (China Gate, The Big Red One).