“If you want to receive a lot of gifts for your birthday and read a lot of compliments, take care of it yourself, otherwise everyone will forget.” This is what her friend Anechka told Evlampia Romanova and asked her to help organize a surprise for the birthday of her mother-in-law, whom everyone calls Murlysya. The gift was a great success: a luxurious chocolate puzzle in the shape of a palace and its inhabitants. Having quickly collected all this splendor, the women sat down to drink tea. Lampusha and Murlysa felt sorry for eating such beauty, but Anyuta enjoyed it heartily and... ended up in the hospital! Evlampia and Max turned to Professor Moses Silberkrantz, a famous expert on toxic substances. He came to the conclusion that Anya was poisoned with the venom of the Cone snail, found in a chocolate present. But his colleague Yuri Derevyankin insists that Silberkrantz was mistaken. This poison is obtained from the tooth lizard. And soon Moses Abramovich commits suicide. Why?! Proud Monya did not survive the shame? It doesn't look like him. Wolf and his team begin an investigation, unaware of how many more deaths await them outside the gates of the chocolate castle!