Captain of the scavenger ship Ghost, Wolf Larsen, (Edward G. Robinson) is a heartless tyrant who can tolerate no sign of weakness in anyone, and reigns over his hellish vessel in true satanic fashion. Idealistic writer Humphrey Van Weyden (Alexander Knox) and fugitive from justice Ruth Webster (Ida Lupino) are picked up by the Ghost when their ferryboat capsizes.
Realizing that their chances of getting off the boat alive are nil, Van Weyden and Ruth conspire with embittered cabin boy Leach (John Garfield) to escape. They drift in a small open boat for days, only to return to the Ghost, which has apparently been scuttled by the mutinous crew.
Ultimately, the Ghost sinks beneath the waves, carrying Larsen and Van Weyden to their doom. Ruth and Leach manage to save themselves, rowing toward the safety of a nearby island.