Arkady Renko is trying to adjust to his new life as a family man with a woman who is not his wife and a boy who is not his son. The prodigal Zhenya is constantly running off on his own for days, sometimes in the company of street children, in the depths of the Moscow winter. Arkady also senses things are starting to sour between him and Dr. Eva Kazka. He and his partner Victor Orlov are investigating claims that someone within the prosecutor's office is committing murder for hire and then covering it up. That is until Prosecutor Zurin calls Arkady off to more unearthly matters: the ghost of Joseph Stalin is being sighted on the Moscow Metro. Knowing all too well that Zurin is giving this case to him as a punishment, Arkady attends to the task of handling it without enthusiasm. Meanwhile, his suspicions begin to be directed towards two fellow detectives: Nikolai Isakov and Marat Urman - both OMON veterans of the Second Chechen War from the town of Tver. Intruding into one of their investigations, he finds evidence that the detectives themselves killed the man in question, and later also his wife while claiming she "swallowed her tongue" in prison. After further incidents on the Metro, Zurin assigns Arkady to conduct an 'unofficial' investigation, his cover being inquiry into supposed death threats directed at Platonov - a paranoid old communist chess grandmaster.