1788 Russia once again grappled with the Ottoman Empire for control of the Northern Black Sea region and the Crimean Peninsula. The Turks, having suffered a series of defeats, turned for help to the Russians' longtime enemy - Sweden, and King Gustav provoked Catherine II to declare war. The young and widowed captain of the second rank Alexei Mikhailov saves the talented Tula gunsmith Usov from suicide, who revealed the secret of smelting damask steel, so necessary for the manufacture of sabers and broadswords for the active army. Usov brought samples of new damask steel to the capital, but it was robbed. Mikhailov and his friend decide to help the master find the thieves. As a token of gratitude, Usov gave the captain a damask damask ring - a completely nondescript little thing. But it was this gift that pulled the whole trio into a chain of incredible adventures!..