Lost Souls of Willowbrook

Sage Winters has always known that her twin sister, Rosemary, is a little out of this world: she perceives life too acutely and needs protection from a hostile world.
Rosemary died of pneumonia six years ago, and Sage, now sixteen, still... misses her. The girl is very lonely: her father abandoned them, her mother died in a car accident, and her stepfather Alan would happily get rid of the burden of his stepdaughter. And all the more terrible for Sage is the discovery that her sister did not die at all, but was sent to Willowbrook, a notorious government institution for disabled children located on Staten Island.
Sage, who rushes in search of Rosemary, has no idea what horrors she will face.