Nocturne for the General — John Trenhaile

Espionage thriller. Stepan Oovin, once chief of foreign intelligence for the KGB, now prisoner in a camp at the northernmost tip of Russia. Povin is a traitor: Early in his career he was converted by the Russian Christians he had been sent to persecute. He then worked with the West whenever Soviet ambitions veered out of control. But Povin has not been shot for treason because he unknowingly holds the key for a code that KGB chief Kazin desperately wants to break.