A trespassing gang of boys encounter a ghost in the ruins of a castle. When they rescue the ghost who is caught in a trapset, they become allies in a fight to prevent ruins from being turned into mushroom farm by the city authorities.

The ten-year-old orphan Borisek is fathered by the entire military unit. The boy serves there with determination as a medic. When he and the soldiers reach Bohemia, he meets the mother of the soldier he saw die, but for a long time he does not find the courage to tell her the cruel truth...