1660: Winter has settled thick over a sleepy village in the Bavarian Alps, ensuring that every farmer and servant is indoors the night a parish priest discovers he's been poisoned. As numbness creeps up his body, he summons the last of his strength to scratch a cryptic sign in the frost. Following a trail of riddles, hangman Jakob Kuisl, his headstrong daughter Magdalena, and the town physician's son team up with the priest's aristocratic sister to investigate. What they uncover will lead them back to the Crusades, unlocking a troubled history of internal church politics and sending them on a chase for a treasure of the Knights Templar. But they're not the only ones after the legendary fortune.