China Mieville, an adult SF author, offers his first book for younger readers. Zanna and Deeba travel from their comfortable London neighborhood into UnLondon, a city that mirrors many of the familiar places, sort of. Zanna is the Schwazzy, the one chosen and destined to save the residents of UnLondon from the encroaching smog. However, it is Deeba who returns to UnLondon to fulfill the prophecy when Zanna is overtaken by the tendrils of the omnipresent smog. Mieville has fashioned an interesting territory with UnLomdon. Rooftop dwellers prefer roofs that hover a few feet off the ground (fear of heights, don't you know?), where garbage can take om a life of its own, and where the smoke and fog can become smombies and other evil creatures who threaten the welfare of both UnLondon and London itself.
Short chapters move the story along rather briskly and introduce all the key players (and there are quite a few including ghosts, utterlings, and unbrellas and rebrellas). The plot twists and turns. There are plenty of sketches (by the author) to give readers an idea of the appearance of the various creatures that inhabit this world. There's humor, some pointed political humor as a matter of fact, suspense, mystery, and danger: all ingredients of a dandy novel with a twist of sci fi and fantasy in the blend. For those younger students who are god readers, Mieville's novel can offer a developmentally appropriate read with a satisfying level of complexity.