Cambridge, 1348. The life of the city and the university is darkened by the anxious anticipation of the Black Death, a plague whose merciless blows have already devastated half of Europe. The disease has not yet entered the city limits, when the peaceful university life is disrupted by terrible and mysterious events. It all started with the discovery of the body of Sir John Babington, master of St. Michael's College, at the Bishop's Mill. Soon another dead body is found in the college - this time the elderly Brother Augustus, the oldest of the monastic brethren. Doctor and scientist Matthew Bartholomew, who is investigating the incidents, comes to the conclusion that both deaths are not accidental, but are somehow connected with the personal secret seal that belonged to the late Sir John and disappeared after the tragic event...