The series "Mosgaz. Cherkasov's Last Case" is a continuation of a Russian retro detective story about the adventures of a principled and talented detective, Major Ivan Petrovich Cherkasov. The events take place in 1981, when the authorities threaten to suspend the hero from investigations after another official violation. Cherkasov realizes that he is getting old and decides to retire of his own accord. But before he goes, he wants to spectacularly close his final case. Meanwhile, a young officer, Major Kovalyov, joins the department.