The year is 1834. A passenger ship, the Esteban, departed from Alexandria, Egypt before news of a plague outbreak could reach its ports. Sailing via Sevilla and London toward the New World, it finally arrives off the coast of New York — only to find itself immediately placed in quarantine. On board are an assortment of passengers and crewmembers, who, as tensions rise, seem to have history together.
On the thirty-seventh day of its forty day detainment, a passenger dies. Not from plague — perhaps — but in such a way that raises suspicion. The authorities refuse to allow anyone ashore until it is proven that contagion is not to blame. And so the passengers remain, three days adrift in enforced proximity, locked between sea and sickness, overshadowed by the possibility that a killer walks among them. Or perhaps King Pest has already come aboard.
To make matters worse, a Great Detective by the name of Dupin is on board, and takes on the task of finding the culprit. This is unlucky for the crew and passengers of the Esteban, since everyone has something to hide, and most especially, something to lose.