Adding a supernatural element to the urban cop story seems to have hit the crossover-genre audience with a bang. I started Broken Homes shortly after finishing Paul Cornell's London Falling (2013), which caused a little confusion—both are part of sequences in which the mean streets of London are policed by a force which needs to add magic to its arsenal, but Aaronovitch's novel is in fact the fourth installment of the adventures of Peter Grant, a rookie cop of Sierra Leonean ancestry who has found himself recruited to a unit investigating monstrous crimes with an occult flavor. Some rebooting was in order, and I eventually found that Broken Homes is probably not best read as a stand-alone. It is, however, an entertaining blend of the secret history and the up-to-date human geography of London.

This is the "rather lowly and half-forgotten special unit of the police force which gets the dirty jobs" routine, but with a difference. Grant is part of a unit known as the Folly headed by one Nightingale; a patrician old-school policeman (and last of the English Wizards) who acts as a kind of exasperated headmaster to his juniors/apprentices. There are back-up experts such as Dr Abdul Walid and Harold Postmartin. Grant's fellow-apprentice, Lesley, has had her face removed by a villain in a previous installment and wears a mask. Other characters include Peter's formidable mother, his jazz-playing dad (whom we see in performance), and the tutelary deities of several of London’s rivers. Most of the characters are introduced in the course of the plot, assuming that we will know them; this offers no problems. (In one instance where it might—the Folly's resident domestic Molly—the lack of description is the point.) What seems to be a murder, a birthday-party conjuring which got out of hand, and a suspicious suicide in the London Underground are thrown at Peter in quick succession. Then we are swiftly into the ingeniously connected major plot strands. These include the mutilation of a book thief who may be an associate of the main villain, the Faceless Man; another rogue magician (the Russian Varona Sidorovna) on the loose in London; and increasingly weird things happening on Skygarden, an architectural masterpiece of a housing estate in South London which seems to have been designed to become a kind of storage battery of magic. Grant and Lesley (with dog Toby) go undercover on the estate to try and find out what the housing-scheme designer Erik Stromberg was all about, and what part the estate's management/security company County Gard is playing in all this.

The failings of modernist social architecture are perhaps an obvious target, but Aaronowitch has a lot of fun here—"the lifts only went to every other floor and Stromberg had cunningly managed to combine some of the disadvantages of a terraced street with all the disadvantages of a tower block" (p. 190)—though social activist Jake Phillips reminds us of the less cynical motives of such developments: "'I've lived here for over forty years but I can still remember what it was like before,' said Jake and then proceeded to tell me in great detail, including with statistics, about the outside toilets, the damp, the overcrowding, the bomb sites and just how vile a sublet terraced can be when there's a lot of you sharing the same bathroom" (p. 230). Peter Grant is an engaging character; slightly dim, too prone (for Nightingale's liking) to say "me and Lesley" or "me and Toby" (and by halfway through the book I think I'm agreeing with Nightingale), but by no means stupid and certainly observant and street-savvy enough to make him a good cop. His self-reflective comments on policing, housing, and his relationship with his mum are wry and always amusing. Aaronovitch's magical undercurrents are dark but (despite the rather horrific episodes around the "Faceless Man" encountered or alluded to) light enough to make this an urban fantasy in the modern sense rather than, say, the plumbing the Lovecraftian depths of, say, Ramsey Campbell's early Liverpool novels such as The Doll Who Ate His Mother or To Wake the Dead (1976). Parts, in fact, seem to echo J. K. Rowling more than Lovecraft: there is an explicit reference when Nightingale takes umbrage at Grant calling his old school "Hogwarts," and Aaronovitch's system of magic is certainly close to that taught to Harry Potter: "I was trying to perfect a forma called aqua which, for those of you who didn't have a classical education, is a base forma for manipulating water" (p. 29); "I started adding second-order effects with impellor, iactus, palma and my personal favourite scindere" (p. 236).

But, if Harry Potter, this is Harry Potter with hard-boiled wisecracks. There are a number of twists and turns (and reminders of earlier twists in previous novels) which make this much more than a light read. One character, in fact, ends up dead not long after being introduced, despite being apparently set up for significant development. Tricks like this make Broken Homes more than a light comedy: the reader always needs to be on their toes. If "urban" in "urban fantasy" means anything, it is the repartee and cynicism of urban life which drives the tone and here Aaronovitch delivers the goods. He seems to have walked the streets and observed the characters. There is a lot more here than just the neat idea to combine police thrillers with fantasy magic: this is, of course, London, a city whose name goes back to an almost-forgotten god and whose rivers (as the sequence will remind us) include more than the Thames. It is a city where over a hundred languages are spoken and where world-famous landmarks mingle with virtually unknown villages. It is the city where Holmes and Moriarty (both referenced here) fought out their rivalry. All big cities are cities of mystery, but London's mysteries seem to get turned into literature more than most, and Peter Grant, learning the magic underlying the city, is every-Londoner.

Broken Homes is entertaining as it is—but it needs its predecessors. There is also a massive plot turn right at the end which will kick-start readers who have been with the sequence from the start into anticipating the next installment, but whose emotional impact may be far less for those who have simply picked up this book to try it out. As noted, not a stand-alone: but very much a series to be read and enjoyed.

Andy Sawyer is librarian of the Science Fiction Foundation Collection at the University of Liverpool Library, and a widely published critic. For ten years he was Course Director of the MA in Science Fiction Studies offered by the University's School of English. He is Reviews Editor of Foundation: The International Review of Science Fiction. He recently co-edited (with David Ketterer) Plan for Chaos, a previously unpublished novel by John Wyndham and (with Peter Wright) Teaching Science Fiction in the Palgrave "teaching the New English" series. He was the 2008 recipient of the Clareson Award for services to science fiction.