On the night of July 28, 1870, ten St. Petersburg residents, all of them connected in some way with the aristocratic Tolstyakov family, receive threatening messages from a mysterious person calling themselves '10.' At first it seems like some sort of strange joke, but then, one by one, they begin to be murdered. And it seems that '10' is actually one of them... This book is heavily inspired by And Then There Were None by Agatha Christie.