Tulle, Trulle and Mulle are three troll girls who can make themselves invisible by touching the great invisibility stone at the edge of the forest while saying some magical words. This means that they can mix with humans without anyone seeing them, and they find it very exciting and great fun to look at all the things that people do, especially the children. But they also learn that people are not always nice to each other, and this is when Tulle, Trulle and Mulle decide to help them a little, and since they can make themselves invisible, they can also make things happen. Also, they can make all kinds of funny voices, and they are very inventive in their own way. Strange things begin to happen to the people in the village; the skeleton at the school comes to life, a grumpy daddy gets a clown's nose, a chocolate gets very upset because it was stolen, a piece of litter has a serious talk with the litterbug, angry snowballs fly through the air all by themselves, a kitchen comes to life to help a mum who has dust on her brain and, finally, we hear about all the packages that disappear on X-mas Eve.
