Spy Story (Secret File, #6)

An attempted murder, the defection of a highly placed KGB official, and an explosive nuclear submarine chase beneath the Arctic Ocean seem to have little connection to one another. But they are the sparks that propel Pat Armstrong — also known as Harry Palmer — into the heart of a brutal East-West power play.
And when Armstrong returns to his own apartment — where someone who looks and dresses just like him has taken up his identity — we are drawn into the world of spies and counterspies, plots and counterplots, that is Len Deighton's unbeatable trademark.