Erik is convinced he has a stone for a heart. That's why he doesn't mind that his parents have no time for him or that he has no real friends. When his family moves to a villa they inherited from aunt Brunhilda, he discovers another family living there - Maria and her dad whom Erik's parents want to kick out. When the family gets an eviction notice, Maria activates her secret plan to bring back her missing mother to save them. Together they end up on a fantastical journey to the In-Between-World and Erik learns how hard it really is to wear a heart of stone.