A chance step can change a person's fate. A St. Petersburg historian receives an extraordinarily lucrative grant from a foreign foundation to research certain aspects of the Russian Civil War. In the course of his work, a mysterious episode surfaces: in July 1918, Comrade Trotsky, chairman of the Revolutionary Military Council, visited the provincial town of Osovets, where a strange infernal ritual was performed… Suddenly the coordinates of history are transformed. The whole picture of the world changes fundamentally. The protagonist of the novel is forced to accept the fantastic hypothesis of the devil's (or god's) continuous interference in human reality, and this tragic phantasmagoria, born three thousand years ago, begins to materialize in modern Russia…