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.