Captain Ffynlo Quick, a Manxman, is the captain of a three-masted schooner, Amaryllis. On the owner's death he acquires a share of the ship by joining in a 'tontine'. Each of the tontine's five members has invested the same amount of money in the venture and the annual profit will be split between them. If any member should die, his share would be divided between the others. The story tells of the various adventures, which befall the ship and her crew including storm, collision, dangerous cargoes, and, on one occasion, the saving of a steamer in peril, resulting in a salvage claim in the Admiralty Court. Threaded through this is the story of the relationship of the members of the tontine. Their deaths, one-by-one, often in strange circumstances, leads eventually to the dramatic conclusion.