Following the discovery of a mysterious "sea ore" indigenous to a specific island, the military becomes involved in extracting this newly found resource. Death row inmates are assigned the hazardous task of retrieving the ore from beneath the water, while soldiers are recruited to stop any escape attempts. By the time Credo arrives as part of the latest cohort of guards, the operation has already been underway for 10 years. He deduces that a particular young laborer must have been born on the island and, absent intervention, is destined to perish there as well—since the ore acts as a slow-acting killer that feeds on every new body added to the seabed.