Magical police reading: "The Rivers of London" by Ben Aaronovitch

Just now and then, a combination of cover design, blurb and the mood of the moment induces a serendipitous book purchase. This is one reason I hope that bookshops never disappear - this can't happen in the same way on Amazon. The bookshop in question was (again!) the small Foyles in St Pancras railway station, which is developing a talismanic status as the home of the random purchase.

"Rivers of London" is not a work of life changing literature. I was slightly put off to see that it is explicitly set up as the first in a new series (you get a sample chapter of book 2 at the end). It is, well, close to pulp fiction. It will not be to everyone's taste by any means, and, as I subsequently discovered, falls into a genre much discussed by almost exclusively male sci-fi/fantasy bloggers with weird avatars. Ben Aaronovitch, it seems, is known principally to these people as the writer of Doctor Who scripts...

And yet, my dear highbrow, literary audience, this was a most enjoyable between-book, full of clever ideas, smart urban wit, twists and turns and magic to please a streetwise Harry Potter afficionado. Harry Potter is indeed directly referenced by one of the characters in the book, a Metropolitan Police Detective Inspector wizard, to explain what he is not. The success of this novel is down to the way it combines down-to-earth policing on the streets of a very recognisable London (the streets and pubs are real) with a subterranean layer of magic and myth either under the surface of the city or unobtrusively mingling with it. The worlds are not separate, à la Harry Potter, but entirely integrated, making London exotic and magic normal. (Peter Ackroyd does this too, albeit in a much more highbrow way, for example.) Similarly, day-to-day policing (numerous references to the banal chore of policing Friday-night drunks) and procedure mix with handling violent outbreaks of the paranormal, the job of a quietly sanctioned police division lodged in central London under the leadership of a venerable police-wizard, with a devotion to Sir Isaac Newton and the learning of Latin.

The story, about which I shall reveal little, is that of a streetwise, mixed-race police constable, just out of probation, who somehow needs to avoid assignment to a tedious back-office job, the main purpose of which is to free up "real policemen to do real policing". Our rather likeable hero, Peter Grant is his name, through a set of bizarre circumstances, finds himself assigned to Detective Inspector Nightingale, a figure treated with much disdain by "real coppers", but who takes Peter under his wing as an apprentice as they have to tackle an outbreak of paranormal crime, the work of a very sorely aggrieved 18th century ghost.

In some ways, the sub-plot, which is all to do with calming down a territorial dispute between two clans of fractious river spirits along the Thames and its tributaries - the old white Old Man Thames and his entourage, who moved up-river at the time of the Great Stink, and the matriarchal band of Nigerian immigrant water nymphs led by the glorious figure of Mother Thames, who reign over the polluted and generally hidden watercourses of the capital - is even more engaging. This is smart London multiculturalism at its witty and at-ease-with-itself best. Just a lot of fun, and panders nicely to that fascination felt by many (me too) held by hidden rivers in urban settings.

So there you are, a fun book, a page-turning story, funny and modern. If you have any sort of weakness for this kind of thing, you'll love it. If, reading this, you shudder at the thought, this is not for you.

The fascination of subterranean rivers in London