Leningrad, 1965. KGB Lieutenant Colonel Mikhail Shirokov is informed that his old enemy Alexander Stroganov, nicknamed Graf, a former punisher and saboteur who worked for German intelligence during the war, has been spotted in Leningrad. With the help of the remnants of the White Guard underground, sabotage group "Zigzag" and "mole" in the ranks of the police, he tried to implement a sophisticated plan to destroy the city: the explosion of five symbols of the revolution, including the Big House. Young Mikhail Shirokov, then still an operative of the NKVD, and his teacher Senior Lieutenant Eremeev prevented this catastrophe, but the Count managed to get away. Shirokov checks all the Stroganovs, now living in Leningrad, suspicion falls on the projectionist. And indeed, he and his wife Laura are thrown into the USSR by American intelligence. Their goal is to kidnap a major nuclear physicist and take him abroad. Shirokov and his task force follow the trail.
