Summer 1905. Southern Sakhalin. The young doctor Georgy Rodin, together with his brother, the disgraced intelligence officer Boris, in the partisan detachment of staff captain Grotto-Slepikovsky heroically fight against the Japanese invaders. However, favorable fate again gives the brave men a chance. The Minister of War unearths Boris's development - the plan for Operation Three Rubies. Together with the beautiful Maria Ocheretina, a technical intelligence specialist, the brothers will have to go to Europe to get artifacts that could turn the tide of the Russo-Japanese War.