Children's crime novel reading

A precious painting is stolen from a church in Val Lumnezia. It's huge and doesn't really fit through the church door. How did the thieves manage to get the painting of the Battle of Lepanto out of the church? Who is behind the sophisticated theft? The police suspect the Gadola family, who spend their holidays in the Lumnezia and had visited the church shortly before. In particular, the mother, a proven art expert, is targeted by the police. The children Laina, Laura and Linus decide to solve the case. Even though the three are not particularly interested in the culture of the valley, it is precisely this that puts the siblings on the trail of the perpetrators. The shape of a church tower, a well-known counting rhyme and the example of the "Valerusas" - the brave Lugnez fighters - help the children to confront the thieves. The most important clue to the perpetrators, however, comes from a crazy old organ player, with whom the siblings consume mountains of omelets.