Lasse and Maja run a small detective agency together. Meet them in a series of puzzling mysteries for primary school readers. The stories are set in and around the small town of Valleby, and have a rich gallery of characters to be captivated by on the exciting road to solving the mystery.
Desperate dog owners in Valleby are charged exorbitant amounts of money by brazen dognappers. Lasse and Maja realize that time is of the essence and pick up the trail. A trail that leads them straight into the darkness of the Bio-Rio movie theater auditorium!