Ulm in 1368: The young stonemason Wulf Steinhauer travels to the trading metropolis to work on one of the most magnificent churches in the world - the Ulm Minster. After discovering that he is not the offspring of a craftsman family, but the illegitimate son of the Countess of Württemberg, he is also driven by the search for his biological parents to the free imperial city. Upon arrival, Wulf falls in love with Brigitta von Ensingen, the daughter of the master builder. Brigitta reciprocates his feelings, but Ortwin, the treacherous assistant of her father, has also set his sights on her...