...The beginning of the 20th century. The great empire of Russo-Prussia - a union of German diligence and Russian ingenuity - has recently gained power, managing to become a world leader. The empire has many enemies, both open and secret. Kirill Benediktovich Brenner is a former imperial landing ritter, now a private detective for hire. He lives with twin girls and doesn't like to remember the past. His next assignment—the search for the missing young son of Countess S., the victim of a serial killer terrorizing the city—leads to unexpected results. It turns out that the story is just beginning with the capture of the criminal maniac, and Brenner, by the will of fate, finds himself drawn into a new, deadly investigation...