It’s a bit grim, but a good read, and there are even a few passing references to some Slough House characters, which is fun for fans like me. It offers an interesting contrast between the seedy end of London we see when Beattany has to reach back out to his contacts in the criminal underworld. This is intense and emotionally powerful - and, as much as I love the Slough House books, this might just be my favourite Herron yet.

Dame Ingrid Tearney is still Head (first desk) and busy weaving the devious webs that will lead to her eventual downfall. If you haven't read Nobody Walks and you love the Slough House books then make a point of reading it. Bettany might have thought he'd left it all behind when he first skipped town, but nobody ever really walks away.

He is the author of the Slough House espionage series (soon to be an Apple TV+ show starring Gary Oldman and Kristin Scott Thomas), four Oxford mysteries, and several standalone novels. It is taut, carefully paced to perfection, scary with regard to MI5, sad in the circumstances of a son's death, brilliant in the former spy's ability to foresee the plotting of the head of MI5, hilarious in some of the torture scenes enacted and simply satisfying.

For 21st century spies and politicians, I think the torch has been handed to Herron, who has run with it. This book almost feels as though it was written to give Tearney a showcase to prove why she’s even more formidable than her subordinate. But more than a few people are interested to hear Bettany is back in town, from incarcerated mob bosses to those in the highest echelons of MI5. Although he had given his testimony behind a screen, there were many in the McGarry clan who would be quite pleased to get their hands on Bettany for betraying them. This is not like the Slough House series, except for some of the wonderful turns of phrase and some of the grittier action.Mick Herron introduces Tom Bettany, a man with a violent past and only one thing to live for: Avenging his son's death. But this is really Beattany’s story and from the beginning you get the sense that nobody will be walking away clean from this story. Tearney] resembled the more benevolent kind of witch, the type to dish out helpful potions when love let you down.