Petrov, Vasechkin and Masha go on an excursion to Lermontov places in Pyatigorsk. Having met their old friend, the Strange Janitor, the trio gets... into the nineteenth century! Friends decide that this is their chance to save the life of the legendary poet and prevent a fatal duel. This is how the newest, ordinary and incredible adventures of Petrov and Vasechkin in the Caucasus mountains begin.
