When the Las Vegas's Riverboat Casino starts to burn down, bald, overweight Ricky Smith nosedives five floors into the pool. After this death-defying jump, Smith, a one-time looser, is miraculously transformed into a major-player winner. Battered and drenched, walking across the street to another casino, he begins a million-dollar winning streak at the tables. But ex-cop Tony Valentine soon arrives, begged by the Strip's casino owners to prove that Smith's - 'Mr. Lucky's' - impossibly successful winning streak isn't on the square. With his finely honed grift sense and a knack for spotting cheats, Tony Valentine finds he has few alternatives - and all of them are treacherous.