A Man of Shadows - Jeff Noon

The brilliant, mind-bending return to science fiction by one of its most acclaimed visionaries. Below the neon skies of Dayzone - where the lights never go out, and night has been banished - lowly private eye John Nyquist takes on a teenage runaway case. His quest takes him from Dayzone into the permanent dark of Nocturna. As the vicious, seemingly invisible serial killer known only as Quicksilver haunts the streets, Nyquist starts to suspect that the runaway girl holds within her the key to the city's fate. In the end, there's only one place left to search: the shadow-choked zone known as Dusk.