John le Carré's Tinker tailor soldier spy

Some say George Smiley is in innocent retirement. Others say he was sacked after the Czech scandal. But all agree that nobody ever leaves the 'Circus' without some unfinished business. Brought out of retirement to trace an enemy infiltrator in the department where he was once the prize employee the shy and retiring master of espionage moves forwards to investigate and finds himself going backwards over very old ground.