March 1181: Thousands of pilgrims flock to the heavily snow-covered Cologne to celebrate Easter when a relic thief throws the city into turmoil. In the cathedral, he stabs a priest, and in the Church of the Holy Virgins, he kills a canoness. The French monk Imbert of Grandmont comes under suspicion. To prove his innocence, Imbert teams up with Jaspar, the young grave digger from Ursula's field, to search for the true murderer. Soon, the two find themselves in the midst of the hunt for the holiest relic in the world. But time is running out: the murderer strikes again and again.