We Thought Ourselves Gods

In a world held together by ancient technology no one understands, where genetically modified children are the norm, science has successfully spliced animal DNA into humans to create an order of shape-shifting soldiers. Most Shifters can only manage one other species; dogs and birds are common. That is, until Sam. He can do five (and counting).
Mack's always been one step ahead of the cops, though she'll never tell you why. It's what's kept her alive in The City for so long. But after one slip up she's faced with an ultimatum; give up her secret, or go somewhere she'd never want to go with complete strangers.
Meanwhile, forces lurk underneath The City, forces with a bone to pick with the society above. Too many bones to pick, in fact. But they've decided that now is their time to resurface. And they know just the people that will help.