After WWII is over, a young officer Volodya Sharapov returns to Moscow to work in MUR - Moskovskiy Ugolovny Rozysk (Moscow Criminal Police). There he meets Gleb Zheglov who is a chief of a squad which fights organized crime. Their main task is to track down a gang "Chernaya Koshka" (Black Cat) which terrorizes the city. Also, they have to find out who murdered Larisa Gruzdeva. Zheglov believes it was her husband Ivan Gruzdev, but Sharapov has his doubts about it...