Spook Street, by Mick Herron

Slow Horse River Cartwright’s grandfather is descending into dementia, which is a particular problem for a former senior member of the British security services. When an attempt is made on his life is it his past coming back to bite him, or the current security chiefs cleaning house? At the MI5 dumping ground of Slough House, there are two new Slow Horses to help or hinder the investigation into a clandestine cuckoo operation with terrorist links. But how far is David Cartwright culpable and will he pay for his mistakes or will his grandson pay for him? As usual the internal politics make everything more complicated, as the power hungry Diana Taverner tries to rid herself of another boss without losing ground. Meanwhile Catherine Standish’s attempt to resign is frustrated as she is drawn back in to help her fellow losers stay alive despite themselves. These books are not stand-alone tales; you need to have read Slow Horses, Dead Lions and Real Tigers to fully appreciate what is happening on Spook Street. Mick Herron’s blackly humorous take on the security services does make one wonder if the world would actually be better off – or at least no worse off – without them.