In the companion to Under Their Skin, Haddix does what she does best: tells an engrossing story and raises important questions. With plenty of material begging to be discussed, this conclusion to the 2-book series will engage young adult readers, even reluctant ones. Nick and Eryn must figure out a way to save the world without sacrificing their newly discovered family in this follow-up to Under Their Skin, which Booklist called "crisp, intriguing, and thought-provoking" in a starred review.

In Under Their Skin, twins Nick and Eryn successfully met their new stepsiblings, Ava and Jackson. But in doing so, the twins found themselves on a mission to discover how to prevent humanity from facing certain doom.

Now, their two families are joined together to save not only themselves, but everyone--human and robotic. Can they figure out how before it's too late?