The small town of Hömpstad is plagued by a series of burglaries and the police seem powerless to stop them.
Ten-year-old Winski meets an old apothecary. He thinks the town needs a hero like Winski and gives him an invisibility powder. This magical substance not only makes people invisible, but also allows them to walk through thick walls. Winski is now supposed to go on a burglar hunt - but he is anything but a hero, is shy and is bullied.
But when his mother's money is also stolen, Winski has to spring into action. Together with the pharmacist, he ghosts invisibly through the city at night, catching one crook after another. However, there is one more suspect: Winski's mother's new boyfriend. The pharmacist fears that Winski is being driven by jealousy rather than evidence.
Is he jeopardizing the secret operation?