The plot concerns the deaths of two operatives; shot by the Stasi as they try to climb the Wall - and is in part a prequel to 1963's The Spy Who Came in From the Cold, the meat of the book consisting of field reports and Guillam's flashbacks, both operational and romantic.
All in the dust bin of history one might have thought except that the victim's progeny are questioning the deaths and threatening to sue; and Guillam is their best hope of unravelling the botched operation.
So Legacy is le Carré - at 85 - taking stock, weighing the past against the present and finding both wanting, although the present perhaps more so - (the young Circus boffins are portrayed as self-serving, venal, pedants with funny names - the snarky Secret Service lawyer Bunny with his "eyes to slits" and "rictal grin" is classic le Carre; another is called Pepsi).
Le Carré returned to the material after being asked to adapt one of the Cold War novels after the success of the recent The Night Manager TV adaptation.
That project was shelved but le Carré's interest was piqued and this short novel is the result.
For the most part le Carré looks back - from a post-Brexit world - with guarded affection at the work of his washed up, self-exiled spies, despite the fact that their legacy lies in tatters around them.
Some have suggested this knotty, brittle novel may be his last book - I'm not so sure - the confidence, precision and scope evidenced here suggest otherwise.
And if ever we need the master of spy fiction at the top of his game it's now.
A Legacy of Spies
John Le Carré
(Viking $37.00)