February 1901. On the outskirts of St. Petersburg, the bodies of two workers with strange puncture wounds are found. The great criminologist Apollo Lebedev and his reliable partner Rodion Vanzarov take on the investigation of this mysterious case. Witnesses claim that a disembodied and faceless ghost was seen next to the corpses. But detectives don't believe in the supernatural. Therefore, the first clue is found quite quickly: the killer was dressed in a black raincoat and a three-cornered hat. Faithful partners will have to find out who organized this bloody masquerade.