Man of shadows, paperback/jeff noon

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 citys fate.

In the end, theres only one place left to search: the shadow-choked zone known as Dusk.