Under the mask of a buffoon. Unexpectedly, the son of the Novgorod nobleman Istoma Yakovlev had to go on the run in order to escape from the wrath of the omnipotent noblewoman Martha Boretskaya, who destroyed his whole family: parents, two smaller brothers and a baby sister. Fate brought the fugitive with an artel of buffoons, but not simple ones. They turned out to be infiltrators of the Grand Duke of Moscow Ivan III Vasilyevich, who had troubles with the Novgorod boyars. Young Istoma vowed to avenge the murder of his family to the nobleman Martha Boretskaya (who was nicknamed Posadnitsa for her great power over Veliky Novgorod) and therefore undertook to find out her plans under the guise of a buffoon. Unexpectedly, the son of a Novgorod nobleman Istoma Yakovlev had to go on the run in order to escape from the wrath of the omnipotent nobleman Marya fa Boretskaya, who destroyed his entire family: parents, two smaller brothers and a baby sister.