Wunderkinds cry too

A rare flute is stolen in the house of a very rich person. The circumstances of the case are such that the investigator Colonel Berg turns for help to Denis, Kolya and Katya. The circle of the suspects is small, but everyone has a motive and the ability to make theft. How to calculate the criminal?
While the detectives conduct the investigation under the cover, something mysterious happens in the house: something heavy falls in the middle of the night-they even shudder the walls, some shadow inaudibly slides up the stairs, and another time, bent into three deaths, drags something somewhere ... And how to explain that the French teacher suddenly ceases to understand in French, and the same person at the same time is in completely different places?