Madrid, winter of 1620. Sebastián Castro, a clerk of good reputation in the town and Margarita Carvajal are happily married, but their happiness is threatened when both of them become the prime suspects in a blood libel: the accusation that Jews sacrificed Christian children and collected their blood, a crime falling under the jurisdiction of the Holy Inquisition. With death at the stake looming large over them, their thirteen year old son, Alonso, begins a desperate quest to save them. His purpose catapults him out of his cosy existence and shows him the stark realities of the world. Despite everything, however, three beacons remain to guide him through the darkness of his misfortune: friendship, hope and a dream.