There's plenty of narrative precedent for China Miéville's hefty but fluffy novel Un Lun Dun; it closely follows the pattern of Neil Gaiman's Neverwhere and Mirrormask, or Clive Barker's Abarat books, and before that, a rich history of fantasy novels about ordinary people sucked into extraordinary worlds. And at heart, it's a standard good-vs.-evil story, with a foregone conclusion and a predictable quest process. But it's a mark of Miéville's creativity that he can stretch an old trope into a newly wondrous thrill ride laced with entertaining exotica.
His story starts in London, where a 12-year-old girl named Zanna experiences a series of extraordinary signs: Her face appears in the clouds, animals bow to her, an excited stranger gushes over her as if she were a celebrity. She learns why when she and her best friend Deeba find their way into UnLondon, an alternate London full of predatory living trash heaps, gecko-legged busses, killer giraffe packs, and shy bridges. There, Zanna is universally hailed as the "Shwazzy," the chosen one destined to save UnLondon from a monstrous threat. So far, so good, in a Harry Potter kind of way. But then things begin to go wrong and the story runs off the rails, in ways it would be unfair to reveal.
Nothing hugely surprising happens; Un Lun Dun is still a standard fantasy about a magic world reaching a cataclysmic turning point, and Miéville doesn't break any new ground there. But while he doesn't reinvent the wheel, he does send it rolling in unexpected directions, and he keeps it moving at an enjoyably breakneck pace. Much of the book turns on the creative surprises he churns out to keep UnLondon colorful and alien. Like Gaiman and Barker, he populates his world with vividly portrayed, often pun-driven bizarreries, like ninja garbage cans ("binja"), smog-zombies, and crawling, eight-legged window-frames ("black windows"). Like Barker, he illustrates his 450-page book himself, with pictures of these creations. And like the best fantasy authors, he fully realizes his imaginary city, giving it form and function to go with all the creepy-crawlies. His UnLondon is where broken and discarded things in the real London go when they disappear, from damaged umbrellas (which all serve a single lord) to dead people, whose ghosts inhabit a ghettoized wraithtown. It's also a place where Miéville piles up enough playful ideas to inject new life into a seemingly exhausted premise.