Peter Grant is back in London – and Lady Tyburn wants to call in a long-owed favour. But when it becomes clear that the case involves an untimely death, ancient magical artefacts being sold on eBay and the Faceless Man himself, Peter knows this it can’t be swept under the carpet – even for an influential Mayfair goddess…

It’s a tricky thing to keep a long-running series feeling urgent and fresh. It’s an even bigger coup to make it better as it goes along – but I think Ben Aaronovitch has done just that. Where the first two PC Grant books were gruesome but light-hearted, the last three (yes, I’m still broadly ignoring Whispers) have all taken seeds sown in earlier pages to deliver adept emotional punches and escalate the meta-plot alongside the case of the week.

All the threads of Peter’s life are interwoven here – his Mum, wanting to know whether he and Bev are planning to have babies (let’s not mention that river in Herefordshire, Peter); Beverley herself, mercurial and confrontational as ever; even feisty Agent Reynolds (okay, there were aspects of Whispers I liked); and – ominously – Lesley May, fresh-faced and in person, with the shadow of the Faceless Man not far behind her. It’s the showdown we’ve all been waiting for since Broken Homes – and it’s worth the wait.

The Hanging Tree starts with a dilemma: can (will / should) Peter hide Lady Ty’s daughter’s involvement in what looks like an accidental death at a party she just happened to be at? A showdown between Lady Ty and the Folly would have been quite enough to keep me licking my lips: Tyburn, with her web of influence, has been intent on restructuring taking control of London’s supernatural policing division since Rivers of London, and the inevitable confrontation with Nightingale has been a long time coming.

But it rapidly becomes clear that – complicated enough though this situation could be – it’s all going to get even more tangled. This isn’t a case Peter can turn a blind eye even if he’d like to (and the mundane police would certainly like to; too many posh parents pulling strings – part of the entertainment here comes directly from the jabs at upper class privilege).

I like The Hanging Tree even more for not being single-minded about its core plot. Along the way, Aaronovitch casually introduces new characters who contribute to the carnage whilst looking well-placed to push forward future plots: the fabulous Caroline and her mother Helena – who, however painful she may be in many respects, is a female witch who can finally call the Folly on their old boys’ club bullshit (YES THERE IS A TRADITION OF ENGLISH FEMALE MAGIC THANK YOU VERY MUCH SIR); and the mysterious Americans, with their apparent intent to wipe out the demi-monde.

Life is never simple for Peter Grant.

Teamed up with the fabulous ‘Muslim ninja’ Sahra Guleed (and I love that Peter almost always does have a female partner; and I particularly like Guleed – who does no-nonsense policing in a completely different way to Lesley May), it starts as a knowing comedy of frustration, privilege and proper process, gets properly uncomfortable about the time the unpleasant Reynard puts in an appearance, and then goes all out with style for the high stakes, high tension, explosive finale. Boom.

Peter has grown a lot. He’s in a steady relationship; his ‘stakeholder engagement’ with the demi-monde has won him access to places most Isaacs wouldn’t be welcome; and his fine line in bureaucrat-o-speak can finally keep his superiors at bay (even if he absolutely hasn’t learnt how to minimise property damage. Honestly, it’s never his fault). He can navigate interviews with rich Dads and stroppy teenagers. He can even just about wrangle a goddess (and I’m not talking about Beverley). But can he shoot his old partner? And what tricks might Lesley have learnt from her new mentor for blowing an old friend’s head off?

The Hanging Tree is a white knuckle ride, and I found it hard to put down from start to finish. I’ll say it again: this series just keeps getting better and better; and I can’t wait to see what it delivers next.

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