Polymorph by Westerfeld Scott

Product Description Gifted with the ability to change her gender and ethnicity at will, a young woman moves anonymously through a futuristic New York City society. She thinks she's unique until she happens upon another of her kind, one who is all-too willing to use his abilities for his own sinister ends. Now she must stop this renegade shapeshifter out to seize control of the entire post-industrial world--where illusion wears the face of reality and the ultimate prize is absolute power! Ads in "Locus".