Don Cossack intelligence officer Ivan Platov, sent to the Ottoman Empire under an assumed name and managing to establish himself in the Turkish navy, finally turns for the Turkish command into Captain Hasan, endowed with trust. Which means new tasks that are on the edge of the possible, and sometimes beyond the bounds. Another Austro-Turkish war engulfs the entire eastern Mediterranean and the Balkans. The interests of most European states are intertwined in a tight tangle of contradictions. The long-standing enmity of the Holy Roman Empire between the German nation and the Ottoman Empire flares up with renewed vigor, since the interests of Istanbul and Vienna will never coincide. Captain Hasan receives the task of conducting a solo cruising in the Adriatic Sea. But during the task, a chain of strange events occurs that are difficult to explain. Oddities accumulate, and Captain Hasan has a strong belief that a new unaccounted for force has appeared, acting on the side of the enemy.