There is something satisfying about coming back to the Rivers of London series. Peter Grant has gone from being a probationary constable who could see ghosts to a reasonably experienced magical policeman who is now expected to deal with supernatural trouble as though it were simply another annoying part of the job.

The Hanging Tree drops him back into London after the rural detour of Foxglove Summer, and it feels like coming home. Although, in Peter’s case, home is a place where river gods have complicated family trees, ancient magical practitioners lurk around the edges of society, and a routine investigation can turn alarming before anyone has finished their tea.

The central mystery begins with a young woman who is found dead after what appears to be a drug overdose. The problem is that her death is connected to a powerful magical family, and Peter soon finds himself investigating a case where the boundaries between criminal investigation and the supernatural become increasingly blurred.

One of the things I continue to appreciate about Aaronovitch’s approach is the attention to detail in the police work. It is not quite as prominent as it was in the earlier books, but it remains an important part of the story. Peter still has to follow evidence, talk to witnesses, work with colleagues and deal with the practical realities of an investigation.

That grounding is particularly useful as the magical side of the story becomes more complicated.

The police procedural realism gives the supernatural something solid to push against. Peter may know that magic exists, but he still has to establish what actually happened, who was involved and what can be proved. The result is that the fantasy never floats away into a separate world. It remains embedded in recognisable London, surrounded by police stations, paperwork, family problems and all the other everyday nonsense that comes with being a copper.

I think that is one of the great strengths of the series.

The Hanging Tree also gives us more of Peter’s developing relationship with Beverley Brook, and I enjoyed seeing that relationship becoming more complicated and more personal. There is a nice chemistry between them, but the romance never feels bolted onto the story. Beverley is very much part of the supernatural world in her own right, and her relationship with Peter is shaped by the very different worlds they come from. Their scenes together are especially enjoyable.

It also gives Peter another reason to take the magical side of his life seriously. When your girlfriend is a river goddess, the phrase “meeting the parents” suddenly becomes considerably more intimidating.

And speaking of intimidating, Lady Ty.

There is something genuinely fascinating about the glimpses we get of just how formidable Lady Ty must have been in her prime. Even now she carries an air of power that makes you think twice before saying anything remotely foolish in her vicinity. The idea that this is her having slowed down is frankly terrifying. I would not want to meet Lady Ty at the height of her powers. I suspect the conversation would be polite, brief and conducted entirely on her terms.

The humour remains wonderfully dry. Peter’s reactions to the increasingly ridiculous situations around him are often funnier than the situations themselves. He has developed that weary acceptance of someone who has discovered that the impossible is not particularly impressive once it becomes part of your workload.

And then there is Kobna Holdbrook-Smith.

His narration has become inseparable from the character of Peter for me. He gets the conversational quality of Peter’s voice exactly right, while giving the wider cast enough individuality to make everyone instantly recognisable. His timing with the humour is particularly good, but he is just as effective when the story becomes darker or more threatening.

There is a real confidence to his performance now. He understands the rhythm of these books, knows when to lean into the comedy and when to let a moment breathe. The result is an audiobook that feels effortless, which is usually a sign of an awful lot of skill behind the scenes.

The Hanging Tree is another thoroughly enjoyable instalment. It brings Peter back into the familiar London setting, develops his relationship with Beverley, gives us some wonderfully intimidating glimpses of the magical establishment and continues to balance police procedure with supernatural mayhem.

It is that balance that keeps working so well. The police realism gives the fantasy weight, while the fantasy makes the everyday business of policing considerably more interesting.

At this point, I am beginning to think Peter should stop being surprised when his work gets weird.

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