Set in 1521 Antwerp, amidst the turmoil of religious conflicts and the dawn of the Reformation, this film follows the journey of twelve-year-old Falko Voeten, the son of a printer. Falko’s father, Klaas Voeten, is apprehended by the Inquisition for producing banned texts, specifically a letter penned by Maarten Luther. This incident inadvertently thrusts young Falko into a mission to assist his father and locate the controversial letter. With the Inquisition closing in, Falko receives unexpected help from Marieke, a Catholic orphan living in the underground sewers. Together, they must race against time to prevent his father from being executed for heresy.