April 1941. According to intelligence received by the Chekists, a fascist sabotage group plans to blow up one of Moscow's defense plants. To find out the plans of saboteurs working under the auspices of the German embassy, the NKVD sends one of its best employees, Sergei Biryukov, to the plant. He finds contact with the fascist agent Keller and finds out that the explosion is scheduled for June 21...

Georgiy Yumatov
Sergei Biryukov
Dmitriy Masanov
Sedoy

Valentin Grachyov
Gromov

Mykola Hrynko
Keller

Fyodor Nikitin
Franz Rediger

Igor Dmitriev
Otto Breyer

Arkadi Tolbuzin
Stepanov

Tamara Syomina
Tanya
Irina Korotkova
Zina

Nikolay Grabbe
'Gruzchik'

Ivan Ryzhov
Osipov

Lyudmila Gurchenko
Klava Ovcharova

Tatyana Konyukhova
employee of the NKVD

Lyudmila Shagalova
'Gruzchik''s partner

Irina Kolpakova
Kitri