... Beginning of the 20th century. The Great Empire of Russo-Prussia - an alliance of German execution and Russian ingenuity - has recently gained power, having managed to break out into world leaders. The empire developed many enemies, both overt and covert. Kirill Benediktovich Brenner is a former imperial landing ritter, now a private investigator for hire. He lives with twin girls and does not 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 with the capture of the criminal maniac, the story is just beginning, and Brenner, by the will of fate, is drawn into a new, deadly investigation...