The story follows the adventures of the narrator and his journey from the Kerguelen Islands aboard the Halbrane. The narrator is a wealthy American, Jeorling, who has entertained himself with private studies of the wildlife on the Kerguelen Islands and is now looking for a passage back to the USA. Halbrane is one of the first ships to arrive at Kerguelen, and its captain Len Guy somewhat reluctantly agrees to have Jeorling as a passenger as far as Tristan da Cunha. Underway, they meet a stray iceberg with a dead body on it, which turns out to be a sailor from a ship named Jane. A note found with him indicates that he and several others including Jane's captain William Guy had survived an assassination attempt and are still alive...