In Italy, 1492, King Claudio sends Mangus the Magician and his faithful servant boy, Fabrizio, to Venice to steal a manuscript that explains a revolutionary way of accounting—double-entry bookkeeping. The manuscript is written by the most famous mathematician in the world, the Franciscan Friar, Luca Pacioli. And gaining knowledge of this bookkeeping method could secure one great profits. 

But Venice is a dangerous place, full of informers, prisons, and harsh punishments for those who steal its secrets. When Mangus is snatched away into prison, it is up to Fabrizio—and his mysterious new friend, Bianca—to navigate the countless islands and foggy canals to find Friar Pacioli before their enemies do, and to save Mangus from being executed.