Mysteriet på Greveholm

The plot follows a family deciding to spend their Christmas on the country. They intend to rent a small house, but stumble across an old castle. Mistaking two thieves for the owners they "rent" the abandoned castle. Soon their children, Ivar and Lillan, discover that the castle is haunted. At first the ghost seems to be evil, but soon the children (who are intrigued instead of terrified) befriend it. However, there is something else in the castle: something even the ghosts are frightened of.