Mister Who. Detective from Petersburg

Parents sent Sashka to his uncle in St. Petersburg for a whole month. It was a surprise for the boy that Archibald Panteleimonovich is a real detective! And now he is working on a very complicated case: a Maltese dog with an incredibly expensive necklace around its neck has been stolen from the gallery "Burnt Orange!"
Of course, Sashka must participate in the investigation. After all, he was nicknamed "Mister Who" for his curiosity, and he also loves dogs! The boy visits the gallery in search of clues, goes to the dog shelter with his new friends, and meets the inconsolable owner of the loss. But it seems someone is trying to confuse all the tracks…