An Iranian boy moves to Luxembourg and forms a friendship with a girl with whom he has no language in common.
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 is bullied at school, or that he has no real friends. When his family moves to a villa they inherited, he is confronted by Maria whom Erik's parents want to kick out along with her father. Maria refuses to move and promises to make Erik's life a living hell. As a last attempt to defeat Erik, Maria goes to look for her mother who disappeared two years ago. 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.
In a time of superstition and magic, when wolves are seen as demonic and nature an evil to be tamed, a young apprentice hunter comes to Ireland with her father to wipe out the last pack. But when she saves a wild native girl, their friendship leads her to discover the world of the Wolfwalkers and transform her into the very thing her father is tasked to destroy.