In this sea-going suspense drama, Edwin Rumill (James Mason) is the former first mate of an ocean liner who leaps at the chance to have a vessel under his full command. However, the S.S. Berwind is no ship to write home about, a freighter from the mothball fleet whose captain has recently died. The crew is often ill-tempered, and Mahia (Dorothy Dandridge), the wife of the ship's cook, doesn't make anyone more comfortable with her flirtatious nature. Rumill learns that the bad attitude of his crew has a sinister undercurrent: two of the hands, Leroy Martin (Stuart Whitman) and Henry Scott (Broderick Crawford), have hatched a scheme to murder Rumill and the rest of the crew, bring in the ship as salvage, and sell it to the highest bidder, expecting to earn close to a million dollars. Rumill must rally support if he and the other men hope to survive.