Former lieutenant of the guard Andrei Petrovich Shuvalov, now a captain, at the end of his adventures, puts together an exhibition of flora and fauna for the museum, writes a book and dreams of an heir, but by the will of fate, his grandson, Pyotr Churkin, becomes his son and spiritual successor. The young midshipman begins his research as part of Wrangel’s expeditions. However, Peter considers the transformation of the fleet to be the main work of his life. Russian ships must change their sails to armor in order to become a reliable defense of the Fatherland and raise their authority in the world. And after the Turkish fleet actually captured the Black Sea borders of Russia, it was Churkin who proposed the idea of creating a new mine weapon capable of turning the tide of the war at sea.