The Dutch East Indies, at the end of the nineteenth century. An adventurous captain of an American merchant vessel is looking for a sunken Dutch vessel containing 10,000 precious diamonds. Unfortunately, he's not the only one and then there's also that volcano on the nearby island of Krakatau, waiting to explode in its historical, disastrous eruption...

Captain Ralls fights Dutch shipping magnate Mayrant Sidneye for the woman he loves, Angelique Desaix, and for a fortune in gold aboard the Red Witch.