Moscow, 1882. The action of this short story takes place entirely in one of Moscow’s salons shortly after the conclusion of the case of M. Sobolev’s death.
One of the visitors recounts a mysterious story that happened six years earlier: the disappearance without a trace of one of two twin sisters. Neither the police, which conducted a thorough investigation, nor the father—a wealthy prince who spared no expense on the search—was able to solve it.
Fandorin unravels the riddle without even leaving the room, and even finds a way to document the correctness of his decision.