After learning that the ship he's working on is carrying slaves, sailor and abolitionist Nuggin Taylor (Gary Cooper) engineers the release of his vessel's human cargo. English officials seeking to end the slave trade note his heroism, and soon Taylor agrees to help the British raid a slave ship commanded by the no-good Lt. Tarryton (Henry Wilcoxon). Taylor soon falls for Tarryton's sister, Margaret (Frances Dee), but his romantic life is placid compared to the challenge that lies ahead.