The TV series "Who's There?" is a Russian thriller that combines several stories about unexpected guests. A sudden knock on the door can scare anyone - from a criminal hiding from the law to someone who has nothing to hide from the outside world. Different characters find themselves in similar situations: a young mother with a child in her arms, a police intern, a pilot, and a billionaire. At the doorstep of each of them are guests who really don't want to open the door.