Stepan and Maria are searching for the missing Mikhail Fedorovich, using a "Lie Detector" and forcing the Cossacks to confess various sins. Lena and the Cossacks hide in her museum, where they conduct an excursion and earn money. However, a chase begins for them, and they escape, having received help from museum staff.

Mikhail Fedorovich, accusing Styopa of cowardice, suggests solving the case with a duel in the style of "Pop MMA". In a scuffle, Nazar kidnaps Alyonka, and Maria turns out to be useless. Cossacks and Elena discover how profitable it is to sell ancient coins, but attract the attention of bandits.