Stalin's Ghost (Arkady Renko #6) by Martin Cruz Smith

Investigator Arkady Renko, the pariah of the Moscow prosecutor’s office, has been assigned the thankless job of investigating a new phenomenon: late-night subway riders report seeing the ghost of Joseph Stalin on the platform of the Chistye Prudy Metro station.

The illusion seems part political hocus-pocus and also part wishful thinking, for among many Russians Stalin is again popular; the bloody dictator can boast a two-to-one approval rating. Decidedly better than that of Renko, whose lover, Eva, has left him for Detective Nikolai Isakov, a charismatic veteran of the civil war in Chechnya, a hero of the far right and, Renko suspects, a killer for hire. The cases entwine, and Renko’s quests become a personal inquiry fueled by jealousy.