The teenager Misha Polyakov, being with his mother in a Ukrainian village on vacation with his grandmother and about to return home to Petrograd, offers his best friend Genka to go with him. Suddenly, a white gang of Nikitsky bursts into the village and attacks Misha’s house, where Commissioner Polevoy lives. The purpose of Nikitskiy (aka Nikolskiy) is a dagger located at Polevoy. Saving the commissioner, Misha learns from him the history and secret of the weapon, and receives it for storage with a request to solve the secret. Having returned with adventures to Petrograd, Misha Polyakov with friends begins to unravel the riddle of the dagger, in the handle of which is encrypted text.
Arkadi Tolbuzin
as Commissar Polevoy
Бруно Фрейндлих
as Nikitskiy
Vladimir Shakhmametiev
as Misha Polyakov
Борис Аракелов
as Genka
Нина Крачковская
as Valya Ivanova
German Khovanov
as Sviridov
Наталья Рашевская
as Mariya Gavrilovna Terentyeva
Константин Адашевский
as philatelist
Сергей Филиппов
as Filin
Igor Kasparov
as Slava
Valeri Sebekin
as Vovka Baranov
Viktor Brits
as Misha Korovin
