She Thief — Daniel Finn

The girl, Baz, and the boy, Demi, are master pickpockets. They weave through rich neighborhoods to slip bags off shoulders and wallets out of pockets before disappearing into the crowd. Their loot goes to Fay, who runs a gang of child thieves from her den in the Barrio. This sweltering slum -- in a city that is imagined, but all too real -- is what passes for home to the kids, and Fay is what passes for family.

That all changes the day Demi steals a magnificent blue ring. Soon, the police chief and the Barrio's crime boss close in on Fay, and she begins to break under their pressure.
Baz has never doubted Fay before. She's never been apart from Demi, either. But soon, Baz is left alone to find her way through a world more corrupt than she's ever realized. Here, the lives of children are thrown away without a moment's hesitation. Here, the rich and powerful are just thieves on a larger scale. And somewhere in this wreck of a city, Baz must find the scraps of hope, the small acts of kindness, and the steely strength that will take her back to Demi and wash them both out of the Barrio for good.