If a door suddenly opens in the wall of an ancient castle, this does not mean that you need to enter it. There is a medieval proverb: “the devil loves monasteries.” Especially those whose walls hide a terrible secret, rooted in the deep Middle Ages, and starting life anew in modern times. Going on a bus trip through the medieval castles of Europe, the main character knew nothing about the doors open in the wall. After a bus crash, he and two random companions find an abandoned castle in the forest. Mystical events are taking place in the castle - the main character will have to save an ancient manuscript and a strange cross in order to fulfill an ancient prophecy. The tragedy of his family is closely intertwined with the tragedy of two women, residents of a medieval town that used to be on the site of a castle-monastery, two women - mother and daughter, who once faced the Inquisition.