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.

Having survived the bombing of the Thames Barrier, Adam and Ros recover to find London facing an even greater threat. While attempting to thwart an attack that could jeopardize a historic peace accord, the team unwittingly unleashes a deadly virus.

The BATAA-winning, international hit spy drama returns for a nail-biting tenth and final series. With the truth about Lucas North finally revealed, and following his rooftop showdown at the end of the last series, Harry is facing some complicated questions about the future of Section D as well as some skeletons from his own past.