The movie is based on Barbro Lindgrens popular and absurd comical books Loranga, Masarin & Dartanjang (1969) and Loranga, Loranga (1970). The movie is about the worlds greatest dad that loves pop music and refuses to get a job - because who would then play with his son Masarin? Lorangas dad Dartanjang lives in the woodshed to prevent germs from getting to him. But that does not seem to help because he keeps getting sick all the time.

The old man PETTSON and his cat FINDUS live on a small farm way out in the countryside in Sweden. Christmas is approaching, and Pettson has given Findus the rash promise that THE TOMTE will come around with gifts for him at Christmas Eve. Pettson does not believe in the Tomte, but in order not to disappoint his cat, he decides to build an artificial Tomte - a mechanical TOMTE MACHINE. Pettson has a hard time keeping the project secret from Findus and getting the machine to actually work in due time. But somehow a mysterious magical force interferes...