Friends from a boyish group would like to prove their bravery. Their leader Jenda decides that in the evening they will go in couples to sign on the wall of a dungeon of a desolate and shabby castle Brtník. Adámek and Vendelín put down their names but they run away from ghostly frightening and howling. Jenda and Zrzek sink through the floor just after catching sight of a flaming inscription: "Be off with you, out-landers!" The children long for a clubroom at the castle and therefore Jenda goes to ask for a permission. But Jouza, a manager of the grocery, would like to produce champignons at the castle. The school head-master Vávra fans the children and visits with them the castle and the game-keeper's lodge where he settles on supplying them with beams for a new roof in exchange of planting out new trees. In the evening, while the first night bird is crying, the children see an apparition, a little girl Leontýnka, dressed in an ancient style. She and her father, knight Brtník, inhabit as ghosts the castle and are interfered with the interest of people. But Leontýnka likes Jenda and for a change knight gets to like drinking mentholated spirit called Francovka which is promptly provided for him by Pepa Boháček. That is why Brtník asks for help wood elfs and they, as if by magic, build up overnight the new roof of the castle. The children achieve a permission to create a clubroom and later on they repair the castle themselves - without magic spells. Brtník returns to his ghost home alone. Leontýnka, being given the ox-eye daisy by Jenda from love, stays to live with people.