Stephanie and the LazyTown children decide to repay Sportacus for all of his heroics by giving him a day off - with Stephanie taking over as hero. Robbie Rotten decides to take advantage, and builds a nasty dog which runs amok in the town.

Íþróttaálfurinn has managed to change the villagers' negative attitude towards sports, healthy food and all diligence. But when he leaves and the villagers have to manage on their own, they turn out to be very unstable and easily influenced by the criminal Glanni Glæpur, who turns up disguised as a very rich man. In fact, he has stolen the president's car and intends to corrupt the villagers so that he can sell them un-wholesome powder-food and become mayor of the town.