I have loved all of Mick Herron’s ‘Slough House’ books and this so-called ‘standalone’ thriller is actually part of that series — indeed, it explains much of what happens in the previous books. It is a prequel to the entire enterprise. But it has a very different feel. First of all, there are long sections of the book where nothing much is going on. That’s deliberate. It sets things up nicely. By the second half of the book, it become unputdownable. I love the fact that this book, set mostly in the early 1990s in Berlin, has a cast of characters that will be familiar to readers of the earlier books — but using different names. We recognise them — with one notable exception — because of how they behave or speak. My one gripe is the plug on the book’s cover from Martin Cruz Smith, who calls Herron ‘one of the best writers of spy fiction working today’. That’s ridiculous. Herron is THE best writer of spy fiction today, full stop.