A secret "underground" society has existed on the rooftops of London since the early 20th century, but that society is now at war with itself. A genuine supervillain with night-vision powers and Doctor Doom stylings has raised a small army of skinheads to crush any who would stand in the way of the violent New Age he intends to usher in, which will culminate in apocalyptic war with the street world below. Those who oppose him aren't fighters--they only ever wanted to live "above it all," peacefully apart--but they are much more experienced and knowledgeable about the roofworld. Robert and Rose are strangers when they happen to catch a rare glimpse of the roofworld, but pursuing and exploring it draws them together. Meanwhile, a detective tarnished by his failure to solve a lurid tabloid-headlining case sees the bodies falling out of the sky as his last chance to redeem his reputation and career.
Now, running and swinging over rooftops is a fantasy that really appeals to me, but I'm afraid Fowler bites off much more than anyone could chew by going all-in with a whole society that literally lives on rooftops 24/7, and never comes down to street level as a matter of principle. Even back at the time of writing, before google earth and the whole anti-terrorist surveillance explosion, just between all the various kinds of helicopters (police, media, hospital) flying overhead, people in tall buildings looking out of windows, normal people going up on roofs for any number of reasons, etc., there's simply absolutely, positively, categorically no way such a society could go any length of time before they were detected, reported, investigated, and brought down to earth. That's to say nothing of all the other practical difficulties involved in securing things like shelter and food. That's to say nothing of all the practical difficulties involved in maintaining a permanent infrastructure of connecting lines around the city for them to move building-to-building.
Then, the absolute refusal of the "good guys" to have anything to do with the street world under any circumstances often looked so stubborn and stupid that they completely lost my sympathy. In real life, I never admire martyrs to causes that don't make sense to me. Whenever I hear of someone dying because they steadfastly refused to compromise some absurd taboo, I smile and think, "Good! Hasta la vista, moran." I often felt the same way about the roofworlders. Just to give a few spoilerly examples . . .
Their network of lines between buildings is impressive, but it's still limited in such a way that the skinheads can make a systematic hunt for them along all its routes. When Robert suggests they get the hell off that grid until things cool down by taking the extraordinarily easy and sensible step of just strolling down a fire-escape or riding down an elevator, they reject the very idea out of hand. When more of them get killed as a result, I found myself shaking my head and thinking, "That's what you get for being so foolish and irrational." Then, a situation arises when twelve of them are about to be ritually murdered on a building that's been rendered inaccessible to their normal maneuverings, but that remains entirely accessible in all the ordinary ways from street level. This mass-sacrifice would be as easy for the police to stop as it would be all-but-impossible for the roofworlders to stop. They don't go to the police, and even hinder police involvement, when one stumbles upon the situation. No, they have to do it their way, the unnecessarily and gobsmackingly and hopelessly hard way. And I found myself shaking my head and thinking, "Good--go ahead and let your stupid friends die," and indeed some do get sacrificed as a result.
I have other problems with this book. Most of the main characters are unsympathetic for other reasons on top of those I mention above. Then, Fowler apparently loses track of who's been killed, and shows one character in action after a spectacularly gruesome death. But the reasons above are my real deal-killers. It's a shame--a book set on the rooftops of London?!?--that should be like porn for me. Very disappointing, and not recommended.