It's the year 1260 and the great cathedral - the most ambitious building in all of Christendom - is rising above the streets of Cologne. Far below its soaring spires and flying buttresses, an assassin of unnatural talent surveys his new hunting ground. More shadow than man, the assassin is quick to take his first life. But there is a witness to his crime: a flame-haired thief known as Jacob the Fox. For all his street-smart cunning, the wily Fox cannot shake off the assassin - a cruel, efficient murderer who favours a pistol-grip crossbow as his weapon of choice. With the threat of an untimely death at the end of a crossbow bolt never far way, Jacob's unlikely cabal find themselves faced with a conspiracy born of an unquenchable thirst for revenge, a conspiracy that threatens to tear Cologne apart and stain the city with blood.