In 1348 in a plague-ridden medieval England, young monk Osmund has a secret relationship with a girl named Averill who has taken sanctuary in his monastery. When the disease strikes the monastery, Averill departs at Osmund's urging, but promises to wait one week for Osmund at a nearby forest. Osmund prays for a sign from God to leave the monastery and reunite with Averill. Shortly afterwards, Ulric, an envoy for the regional bishop, arrives at the monastery seeking a guide through the forest to reach a remote marshland village untouched by the plague. Taking Ulric's arrival as the sign to leave, Osmund volunteers to serve as the guide and joins his group, which is comprised of soldiers Wolfstan, Griff, Dalywag, Mold, Ivo, and Swire. The group informs Osmund that the village is believed to be led by a necromancer, who they intend to deliver to the bishop.