The 12-year-old Oliver discovers that his grandfather used to be a monster hunter and is keeping a shadow monster locked up in his secret cellar. When the shadow monster accidentally escapes, Oliver and his younger brother Lasse have to follow their grandfather's instructions and enlist their friends to catch the monster and bring it back - before it is too late! »Monster Busters« is based on an idea of the universe in the children's book series by Jacob Weinreich.
Les exploits d'un groupe de vikings de la fin du 8ème siècle jusqu'au milieu du 11ème, mené par Ragnar Lodbrok, l'un des plus populaires héros viking de tous les temps, qui a régné quelques temps sur le Danemark et la Suède...