As a young doctor, Nicolo Barbaro sets off for Constantinople to seek adventure and escape the confines of Venice and his family's expectations. He arrives in the city just as the Ottoman Turks and the Byzantine Christians are locked in a bitter battle.

Urged to flee Constantinople by his loyal servant, Nicolo deserts his friends and patients and sails back to Venice. When his ship is infected with pneumonic plague, Nicolo has the chance to redeem his past failures. Will he find the courage to stay on the ship and tend to the dying crew? He knows that remaining on board could well cost him his life.