A young cashier of one of the enterprises with a large sum of money disappears. A group of employees of the Criminal Investigation Department is involved in the work.

The film is based on documentary facts and tells the story of an officer in the Japanese General Staff who received the task under the name of Captain Rybnikov to infiltrate the military circles of St.Petersburg. It was exposed after the famous Tsushima battle of 1904, when Japan destroyed the entire Russian Far Eastern fleet.