The Tristan Betrayal - Robert Ludlum

Moscow --- a city under siege by hardcore Communists threatening to plunge the country back into Stalinist darkness. Into the heart of the firestorm, American ambassador Stephen Metcalfe has been summoned to find the one man who controls the levers of power in absolute secrecy --- an official known only as the Dirizhor. His support of the bloody coup will bring the entire world to the brink of nuclear war. Metcalfe is the only man with the cunning to reach him and to convince him to resist. It's up to Metcalfe to change the course of history. He's done it before.