The medieval castle, rising on top of a low mountain, had become fairly dilapidated by the mid-twentieth century, and the family of the owners of the ancient building had long since gone bankrupt, but the descendants of knights and warriors - a famous historian and his son - still love the ancient abode of their glorious ancestors, Their servants also agree with them - the family of the butler, who is convinced that his family is no less ancient than the family of the owners of the castle. And recently, a stray cat has taken root in the castle, and he has an unusual friend who lives in a small cave on the mountainside. He seems to be very interested in everything that happens in the castle. And in fact, everything is not so simple. Castle Hill has its own secret. And the inhabitants of the castle have to go through many amazing adventures. Treasure searches, uninhabited islands, ancient letters, mysterious creatures... And also: the struggle for your love, the ability to sympathize, understand and help...