The screen adaptation of children's Swedish detective stories about the adventures of the police commissar Gordon and his deputy, Paddy the mouse is an animated story of friendship between two very different heroes who join forces to protect the inhabitants of the forest. Will their cunning and prudence be enough to solve another mystery?
During the investigation, Gordon catches a hungry mouse with his hand in the proverbial cookie jar. He quickly realizes that Paddy could not be guilty of stealing the nuts. There is only one law of the forest, says the Commissioner, being nice is legal, being mean is not. So, he asks the clever mouse to help in the investigation and when she proves her mettle, he appoints her his successor. Unfortunately, Paddy may not be up to the new challenge. Will they be able to catch the forest criminals?