To escape the crackdown on casinos, gambling czar Greg Morella moves his operations to the ship Sylvania , anchored three miles off the coast of New England, safe from federal and local police. Mingling with the suckers aboard Morella's ship is reporter Jim Carver, who lulls the gangster into believing that he is his ally. Jim wins the enmity of Max Gates, Morella's trigger man, when he wonders if Gates's embittered girl friend will meet the inexplicable death that befell her predecessor. Soon after, Larry Brill, Morella's crooked manager, begs Gates to help him escape before Morella has him eliminated for embezzlement. Gates arranges for Brill to leave the ship with two policemen after Brill gives him authorization to remove $25,000 from a safe deposit box. After the panic sticken manager leaves the boat, however, Gates informs Morella, who orders Frank and Louie, his hired thugs, to kill Brill. After the murder of Brill, Jim becomes determined to expose Morella, and forces a confession from Gates by convincing him that he will be indicted for the death of his wife unless he testifies against Morella. Before the police can arrest Morella, the secretary to the district attorney turns Gates's written confession over to the gangster, who orders Gates's murder. Refusing to accept defeat, Jim convinces Morella's secretary, Laurie Ogden, with whom he has fallen in love, to tell what she knows to the police. The information enables the police to stage a raid on the Sylvania , and in the confusion, Jim and Laurie take photographs of the crooked gambling devices used on the ship. They return safely ashore with the pictures, but before Laurie can testify in court, Morella orders her kidnapping and Jim is trapped while trying to rescue her. Morella, determined to eliminate them for good, has Frank take them for a ride at sea, but wherever they turn, a police boat, forewarned by Jim, heads them off. In the chase, Jim overpowers Frank and when the police arrest Frank and the others, Morella's conviction in assured and Jim and Laurie are wed.