A random step can change a person's destiny. A St. Petersburg historian receives an extremely profitable grant from a foreign foundation to study some aspects of the civil war in Russia. In the process of work, a mysterious episode emerges: a visit in July 1918 by the chairman of the Revolutionary Military Council, Comrade Trotsky, to the provincial town of Osovets, where a mysterious infernal rite was performed... Suddenly the historical coordinates are transformed. The whole picture of the world is fundamentally changing. The main character of the novel is forced to accept the fantastic hypothesis about the continuous intervention of the devil (or god) in human reality, and this tragic phantasmagoria, which originated three thousand years ago, begins to materialize in modern Russia...