While suspicion in Gruzdeva's murder initially falls on her estranged husband Dr. Gruzdev (Yursky), it gradually becomes obvious that the two cases are connected, as a Black Cat mobster known as Fox (Aleksandr Belyavsky) is implicated in the murder. As a result of Zheglov's successful high-stakes operation to capture Fox, Sharapov inadvertently finds himself undercover at the Black Cat hideout, sparring with the gang's menacing leader, the Hunchback (Armen Dzhigarkhanyan). What ensues is arguably one of Soviet television's most memorable and suspenseful finales.