Who is the dead man whose body, pierced by an arrow, is found right on the border between the urban area and the cathedral square, raising questions of jurisdiction? Free Judge Bernd Ketteler, investigating magistrate and chief police officer of Münster, and his friend Father Martin Tewes are faced with a serious problem. Especially since the case, after the identity of the murdered man is revealed to be a supporter of the Spanish embassy, seems to threaten the ongoing peace negotiations. Shortly thereafter, the body of the prostitute Catharina is discovered, and an assassination attempt is made on the guild member Wilhelm Eickhaus, putting Ketteler under increasing pressure to unravel the threads of the crime, even at the risk of his own life...