Desperate dog owners in Valleby are charged irrational amounts of money by some 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 Rio movie theater auditorium.

Martin Widmark and Helena Willis bestselling The Whodunit Detective Agency series has sold over 12 million copys worldwide. Meet Lasse and Maja, who runs a small detective agency together, 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.

The Movie Theater Mystery is the sixth installment in the series with Lasse and Maja.