Russia, the late 19th century. As the threat of war with Great Britain looms, a mysterious device—a mechanical flea—is discovered within the Imperial Palace. Tasked with investigating the incident is a young officer, Pyotr Ogaryov, who dreams of earning the trust of Tsar Alexander III. In his quest for the truth, he joins forces with Lefty, a brilliant but forgotten master craftsman from Tula. Together, they plunge into a world of intrigue and danger. To uncover a conspiracy, the two heroes must challenge the established order, unravel family secrets, and make a difficult choice between duty and passion. The security of the nation—and their own destinies—hang in the balance.