The Secret Pilgrim (George Smiley #8) by John le Carré

Nothing is as it was. Old enemies embrace. The dark staging grounds of the Cold War--whose shadows barely obscure the endless games of espionage--are flooded with light. The rules are rewritten, the stakes changed and the future unfathomable.
Ned has worked for the British Intelligence all of his life--a loyal, shrewd officer of the Cold War.

Now approaching the end of his career, he revisits his own past. He invites us on a tour of three decades in the Circus, burrowing deep in the world of spies from every corner of the globe.

"Le Carre is simply the world's greatest fictional spymaster!" (Newsweek)

Novels by John le Carré in which the character George Smiley appears. With the exception of The Karla Trilogy, these are standalone works and can be read in any order. (In four out of nine of them, Smiley is only a minor character.)