Dead Ringer

Livvy didn't know her entire life was a lie until she ran away from the only place she ever knew, chased by fire and weapons-toting brutes she once considered friends. Broke, banished from his home city, and reduced to living in a dilapidated house in the Arizona desert, Asher is stunned when the doppelgänger of a notorious singer breaks into his home. Even more incredible is her claim of escaping an underground compound just a few miles away, full of lookalikes of the world's rich and famous.
Livvy doesn't want to trust anyone, but life on the surface is as frightening as it is fascinating, and turning down Asher's help isn't an option. Someone wants Livvy back and will stop at nothing to find her.