This psychological thriller follows a girl with dark secrets to a school with uneasy mysteries of its own. Accused of murdering her grandfather, Angela is dispatched to Hidden Oak, a boarding school where the physically and emotionally abusive faculty plays the Prisoner’s Dilemma with its students for commissary points. Angela forms an uneasy friendship with a group of girls, some of whom later disappear. Cut off from the rest of the world, Angela tries to outwit the faculty to find her friends and save herself. It takes several botched escapes and one mostly successful one for Angela to see that being bad and being dangerous are not the same thing. Dangerous, in fact, might be a desirable trait. The horrors of Hidden Oak are slow to unfold but the ending is rushed, and unanswered questions about Angela leave room for a sequel. Self-reliance and trust are explored using a cast of secondary characters who range from innocent to malevolent. With few exceptions, readers never quite know who is good and who is bad. Gripping, violent and terrifying. (Thriller. YA)