A political extremist (Wilson), on the run after assassinating a corrupt politician, poses as a French sailor in hopes of fleeing the country. On arrival at Boston Harbor, he learns his ship has broken down and is being towed to New York for repairs. Hastily, he decides to stow away on a freighter to catch up to his disabled ship. But to gain access to the ship unnoticed, he kidnaps its sole passenger, Katherine Jason, the daughter of the ship's Captain. Wilson manages to elude a Coast Guard Officer and avoids detection during an on-board search by hiding in Katharine's berth. He assures the Captain he will release his daughter unharmed if he's guaranteed safe passage to his ship. Captain Jason agrees, and to assure Katherine's safety, keeps the abduction from the crew. But Jason's First Mate finds out and alerts the crew to the abduction. Meanwhile, Wilson's attempt to justify his actions to Katherine leads to a brutal assault, leaving her agonized and despondent.