The third year of the First World War, Kyiv. One of the first passenger planes of the empire - "Grand" designed by Igor Sikorsky - lands at the Kureniv Airfield. Six people boarded the plane in Petrograd - aircraft designer Prince Oleksandr Kurdashov with his young wife and four crew members, but only four of them set foot on the ground in Kyiv. Sikorskyi - a former student of the deceased Prince Kurdashov - turns to the legendary former head of the investigative unit of the Kyiv City Police, Heorhiy Rudy, because the police are trying to accuse one of the crew members, in whose involvement in the crime he does not believe. Georgy Rudy hands over the case to his old friend and former deputy - Taras Adamovych, who is surprised by the manner and place of the murder. There are four suspects in total. Only the investigator Taras Galushko has been avoiding any mention of the conquerors of the sky for many years in a row, because he has his own painful secret...