An old, mysterious book, a brewer from the 13th century - and the door to the cosmos of the Middle Ages is already wide open. Niklas von Hahnfurt sets out on the stony path to become the best brewer of his time. From his Franconian homeland, he travels via the Weihenstephan monastery to St. Gallen, the stronghold of the medieval art of brewing. When several pilgrims are murdered there with poisoned beer, Niklas is targeted by the fanatical inquisitor Bernard von Dauerling. A hunt for life and death begins. Niklas' flight takes him to the beer towns of Regensburg, Bitburg and Cologne, and the "beer wizard" even reaches Lübeck and London. But in the end, a final "beer duel" with his mortal enemy is inevitable.