Siblings Asger and Petra have recently lost their father and this is their first Halloween without him. Asger and neighbor girl Esther have drifted apart, but are forced to celebrate Halloween with their families. But when Petra suddenly disappears without a trace, Asger and Esther have to work together to find the missing little sister. They head out into the Halloween night, and in their frantic search for Petra, they encounter the boy Svend, disguised zombies, thieves and all sorts of challenges, before ending up in front of the spooky house where the evil witch lives. Can they find Petra in time?