The Dutch East Indies, in the late 19th century. Capt. Hanson of the "Batavia Queen" is preparing to embark on a salvage expedition. His mistress, Laura, knows the location of a ship belonging to her late husband, a shipwreck concealing a cargo of rare pearls. A diver and a diving bell are aboard ship. But a government agent coerces Hanson into accepting a shipment of convicts for the ship's hold. The wreck lies dangerously close to the erupting volcano on the island of Krakatoa, where Laura's young son attends the convent school...