Just when they're about ready to give up on trying to get pregnant, they hear about a doctor in Slovenia who has nearly a 100% success rate with his fertility treatment. They've never heard of this man before, and they know nothing about what the actual treatment entails, but they are desperate. When they get to the doctor's office, the place is questionable and the doctor himself seems like a madman, but they go through with the painful procedure anyway, and sure enough, it works. It works so well, in fact, that Leslie becomes pregnant with twins.
Ten years later, the side effects of the treatment have taken a tremendous toll on both Alex and Leslie, and they've closed themselves off from the outside world, for the most part. They take turns walking the children to and from school each day, but beyond that, life is spent in secret. So secret, in fact, that much of what goes on in their once-luxurious home is a mystery even to the twins. Adam and Alice are smart, though, and have long since realized that there is something very "off" about the way they live and the way their parents behave. For one thing, they don't quite understand why they need to be locked in their rooms at night.
Adam's been spying on his parents, though, by listening to them at night through their old baby monitor, and what he hears makes him more and more uneasy. Slowly, he begins to fear for both his and his sister's lives, and one night, they run away. Finally out in the world, the twins begin to learn the very terrifying answers to both the questions they've asked and those they've been afraid to ask. Their situation, they find, is worse than they could ever have imagined, and the most horrifying truth of all is that there may not be anything they can do to escape it.
