V.C. Andrews 
Midnight Flight 

They lived on the wild side. Now these bad girls are paying the price.At Dr. Foreman’s School for Girls, the "students" sleep in barns, work on a farm in the blazing heat, and are subjected to ruthless guards who watch their every move. It’s an institution run by the dreadful Dr. Foreman, a woman who delights in administering the worst form of punishmentthe mysterious Ice Room where the girls face their darkest fears. Now Phoebe, Teal, and Robinthree girls from very different worldsare the newcomers in this desert hell. During their stay, each girl will be tempted to commit the ultimate crime of betrayal as Dr. Foreman cleverly tries to turn them against each otheruntil they learn that the only way to survive is to stick together…and fight back.