It soon became clear that a new era had begun. Life split into before and after. It also split the friends Lyuba and Lyudmila-Apelsinchik with their different attitudes to COVID. While self-isolating, the restless Lyudmila secretly goes for a walk in the park. And almost becomes a victim of a maniac. She is saved by a dog that its owner decided to walk in the park at that late hour. The friends decide to help her find the attacker—especially since the next victim, unlike Lyudmila, was not so lucky. Her mutilated body is found in the same park in the morning. And then it gets worse… Everyone is baffled: what kind of maniac is it, and what does the big black dog have to do with it? It seems that very dog is the key that opens the mystery behind the serial murders.