Good buddy work by Cooper and Raft highlight this complicated seafaring yarn. In the 1840s sailor and abolitionist Nuggin Taylor (Cooper) is secretly sabotaging slave ships, working undercover for the British Navy. With loyal friend Powdah (Raft), Taylor tries to gather evidence against British officer Tarryton (Wilcoxon) even though he's fallen for Tarryton's sister Margaret (Dee). But after a sea disaster, Taylor's accused of murder and brought to trial. Will the truth come out in time to save him?