A maniac has appeared in the city, killing girls and young women. He goes on his bloody hunt only on the night of the full moon. The police have been knocked off their feet, but their efforts are of no avail. The killings continue. Information about them was leaked to the press. Just then, the whole city will be seized with panic. And then the Napoleon investigator turns to his childhood friend, private detective Miroslava Volgina, for help. She agrees to help him. And then the unexpected happens. A man is killed on a full moon. Clutched in his hand is a pink silk thread. It is this thread that helps the detective solve a chain of crimes.