It is no use locking young detectives at home - they will still find a way to get involved in adventures. After all, the restless sons of Colonel Obolensky, Dimka and Alyoshka, firmly decided to help their dad in investigating two cases of... bad luck. Clever thieves steal brand new foreign cars from buyers of the unlucky Alliance car dealership. Businessman Arkasha, a friend of Colonel Obolensky, is also unlucky - they threaten him and demand money. Fortunately, Leshka, with his analytical mind, long ago understood how these two cases were connected. Moreover, he even figured out who was behind them...