Based in part on Le Carre's book, this is a fascinating insight into the mind and works of Le Carre / David Cornwell. The documentary mixes interviews with Cornwell in a darkened library with dramatised clips, as he recalls his childhood especially his extraordinarily disreputable father who despite being a complete fraud seems to have influenced Cornwell considerably. He then goes on to explain his role in the secret service and the seemingly deranged minds of those around him, including Kim Philby who seem to thrive on deceipt. Thereafter he has used this knowledge, his fertile imagination and his childhood experiences to craft so many great spy novels.
It is all thoroughly absorbing helped immeasurably by the man himself whose warm treacly erudition cannot fail to keep you entertained. It is interesting that this smooth manner must have helped a lot when he was interrogating and you therefore wonder when being 'interrogated' himself by filmmaker Errol Morris whether everything he claims is true, actually is - he is after all an expert on deception.
The Pigeon Tunnel title is explained at the beginning of the film and goes some way to explaining why most of his books start off being called The Pigeon Tunnel.