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.

Andrei Vysotina, who has just graduated from the Naval Academy, is appointed commander of the ship Derzhavny. The hero challenges the commander of another ship in the Black Sea Fleet, whose wife he was once in love with.

A princess falls in love with a musician and separates from her husband, for which she is separated from her daughter Eliza and expelled from home. In her new marriage, she has a second daughter, Liza, and the sisters do not yet know about each other's existence. One fine day the royal family comes to the city where they live...