A series of identical crimes, cruel, as if subordinated to some strange, wild logic, shook the city. The investigation reached a dead end - the killer seemed to laugh at the investigator and easily, like an experienced predator, escaped unpunished again and again. The most experienced investigators joined the search for the maniac. But it seems that only one person is gradually starting to figure out how to find him - a young student doing an internship at the prosecutor's office. He knows: in order to catch the killer, he must be understood...