Madeline Gray, a young San Francisco woman spending the winter in the tropics, is suddenly called home. Accompanied by her friend Walter Maxwell, she books passage on a schooner owned by Bucko McAllister--aka "The Brute Master" because of his brutal, tyrannical behavior. Once they're at sea a crew member mutinies, locks McAllister in his cabin and sets the ship on fire. Maxwell, Madeline and the remaining crew make it off the ship and to a nearby island, where they make a discovery that they weren't expecting at all.