The US is at war and children are sent to boarding schools "for their protection". Four girls come together and figure out that "all is not as it seems". Each book in the series (4 in all) is written from the viewpoint of a different girl.
Yes, the story line is a little predictable, but it is written for younger children. There's just enough tension to be exciting without being scary. I'm interested enough in seeing what happens to these girls to track down the other books as they are published. There won't be long to wait between stories. All four books are scheduled to be published this year.