Bamse, Lille Skutt and Skalman embark on an adventure that takes them through the Troll Forest to the City of Thieves to save Grandma from the villainous fox Reinard.

Bamse's friends go on a quest to find the Thunderbell, the ingredient that makes Bamse strong. Meanwhile, the sly Reinard pretends to be a good guy to supplant Bamse as the hero of the town and win the affections of Mickelina.

In Bamse and the Witch’s daughter Croesus Vole finds gold in the beavers' dam. To demolish the dam and get the gold he tricks the witch's daughter Lova to enchant Bamse. With Bamse gone, it's up to the children to help each other to stop Croesus - but to do that they have to be friends.