The beginning of the twentieth century. Saint Petersburg. In one of the quiet philistine neighborhoods, murders occur. An unknown murderer began to kill entire families with an ax. The crimes are terrible, but at first glance they are simple and do not promise a long investigation. Moreover, the head of the detective police, Vladimir Gavrilovich Filippov, and his team of experienced investigators get down to business. However, from the very first steps, the investigation reveals some oddities in the picture of the crime. Who is this crazy maniac? Is this the same person? What actually is his motive for killing harmless citizens in a particularly brutal manner? There are more and more oddities and difficulties in the case, the investigation takes detectives far beyond the borders of St. Petersburg, right up to Finland. The threads are woven into a tight ball, which only the chief of the detective police, Filippov, and his assistants can unravel.