In Over Their Heads — Margaret Peterson Haddix

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?