Sixteen years after the events of Mysteriet på Greveholm, a new family moves into the long-neglected castle. Left behind after the Olssons’ departure, the ghosts Jean and Staffan have spent years alone in the dilapidated halls and are delighted to finally have company, eagerly trying to make the newcomers feel at home. But as they settle in, they begin to discover that Greveholm is hiding far greater secrets than anyone ever imagined.