Peter pays a visit to Xenia, who, taking advantage of her charm, lures Peter to bed. Dressed in a man's dress, Varya decides to talk to the emperor. Paul listens favorably to her, but he does not intend to change his order against the cavalrymen. Grand Duke Constantine is subdued by Vari's extravagant act and asks her to stay at court. Tolstoy and Lugin await punishment. In the fortress, they unexpectedly meet Stepan, who tells them his story.

Peter in the house of Xenia learns about the impending coup. He hurries to warn the emperor, but his attempt fails - Kutaisov does not understand the importance of the letter and decides to give it to Paul in the morning. D'Arnie watches Peter and tries to kill him. Palen manipulates Alexander by showing him a warrant for his arrest. Alexander agrees to participate in the conspiracy. Mongo receives a signal that a coup has begun.

Peter, accompanying the Grand Dukes on a walk, suddenly notices that mysterious strangers are shadowing them. Having begun their pursuit, he soon loses sight of them - in one of the alleys, strangers disappear without a trace. Konstantin persuades Alexander to continue the night walk, he liked the owner of the German tavern - Lenchen. Only in the morning the princes return to the palace. Polish conspirators - Tadeusz and Zosia are plotting the kidnapping of Grand Duke Alexander.

Peter and Lugin are conducting their own investigation. They explore the lane and find a secret underground hole leading to an inn. Having found out from the owner who else knows about the existence of the tunnel, they lie in wait for Zosya, but she manages to escape. Varya discovers that the medallion is missing, and informs Peter about it. Peter decides to have a frank conversation with Olga - he cannot forget her. Mongo-Stolypin, knowing what kind of medallion Olga wears on her chest, suffers but does not reveal the secret.

Mongo-Stolypin finds Peter coming to Olga. Olga is afraid of a scandal, but Mongo hides his jealousy and kindly invites Peter to the ball with them. At the ball, Peter confesses his love to Olga, but she, disappointed by the latest events, refuses him. Olga runs away from the ball, and Peter meets Palen's daughter, the adventuress, Xenia. Tadeusz and Zosya try to hurt Czartoryski's national feelings and force him to agree to participate in their plans.

Peter, the cavalry guards, and the Grand Dukes are trapped in a German tavern. Czartoryski tries to warn Alexander but does not have time, a fight breaks out. Konstantin, shortly before this, goes down to the backroom to Lenchen, trying to achieve reciprocity. But meets only surprise. The Grand Duke has a fit of anger, having come to his senses, he discovers the lifeless body of Lenchen nearby. Protecting Konstantin Lugin accidentally kills her husband Lenchen.

Czartoryski saves Alexander's life. Tadeusz is killed. Zoya manages to escape. When the police appear, Peter takes away the Grand Dukes, Tolstoy and Lugin remain with the wounded Okhotnikov. Thanks to Peter, the princes manage to evade persecution. When Peter returns to the tavern, his friends are no longer there - they were taken to the police station. Palen reports to Pavel about the night incident in the city.

The surviving Polish conspirators seek to hide, Zosia threatens the cavalry guards and Czartoryski to avenge their murdered brother. To avoid publicity, Peter takes the Grand Dukes away. Lugin and Tolstoy remain with the wounded Okhotnikov. Mongo-Stolypin is cold with Olga. To avoid suffering, he offers her free family relationships - such as many St. Petersburg couples have. Olga is offended and upset. Palen reports to Pavel about the events of the night.

Peter asks Alexander for his comrades in trouble. Alexander promises to help, but does not believe in a successful outcome of the case - Pavel is adamant. Olga decides to break off relations with Peter, she writes him a letter and gives it to the batsman. The cavalry guards are transferred to the Peter and Paul Fortress, where they must await punishment. Arriving in Cherkasovo, Aglaya complains of her loneliness, she wants to take Varya to St. Petersburg. Pahlen and D'Arny discuss the possibility of plotting against Paul and drawing Alexander to him.

Peter, having received the letter, penetrates the house of Mongo-Stolypin for a decisive conversation with Olga. Olga chases him away. Suddenly, Peter learns about the conspiracy against Paul, he cannot help but warn Olga that her husband is involved in this. Mongo, having been a bystander to the transfer of the letter to Peter, recognizes a familiar envelope. He further strengthens his suspicions of his wife's infidelity and decides to join the Masonic order.