The replacement- Brenna Yovanoff

ackie Doyle is the Replacement. Though he lives in the small town of Gentry, Mackie comes from a world of tunnels. and black murky water, a world of living dead girls ruled by a little tattooed princess. He is a Replacement - left in the crib of a human baby sixteen years ago. Now, because of fatal allergies to iron, blood, and consecrated ground, Mackie is slowly dying in the human world.

Mackie would give anything to live among us, to practise on his bass guitar or spend time with an oddly intriguing girl called Tate. But when Tate's baby sister goes missing, Mackie is drawn irrevocably into the underworld of Gentry, known as Mayhem. He must face the dark creatures of the Slag Heaps and find his rightful place - in our world, or theirs.