There is a murder in the Lombard castle of the Duke of Sforza! And this is in the family nest of the ruling Duke of Milan... No, no one except the owner should know about this, despite the fact that it was not just anyone who died, but the count, the cousin of the Duke himself, who played the role of the figure of the “white bishop” in the party “ live chess” played in the castle garden. But a simple groom nicknamed Dino, who was also an apprentice of the great Leonardo da Vinci, will reveal the mystery of this bloody crime, and at the same time some other secrets of the “Sforza court” according to the tips of the great master himself, who at that time was developing new military equipment and decorating the ducal castle with its unique works. At the same time, Dino will sacredly preserve his “secret of secrets”...