The legendary novel in the genre of “alternative history”! The end of the 20th century... Unknown terrorists blew up the Tsarevich gravity plane, on board which was the heir to the Russian throne. The investigation is headed by Colonel of the Ministry of State Security, Prince Trubetskoy. It turns out that communists were involved in the crime. The prince cannot believe this, since he himself is an adherent of the ideals of communism. Step by step, Trubetskoy follows the entire chain of tracks leading to an ancient house on the territory of the German Empire, where a lonely scientist conducts an experiment unthinkable from the point of view of morality and basic humanity...