Nick and Eryn's mon is getting remarried, and the twelve-year-old twins are skeptical when she tells them their lives won't change much. Well, yesm she says they will have to move. And they will have a new stepfather, stepbrother, and stepsister. But don't worry, Mom assures the kids. They won't ever have to meet their stepsiblings... For Nick and Eryn, this news beging a quest to find out who these other kids are — and why they're being kept hidden, In New York Times bestselling authot Margaret Peterson Haddix's two-book series, the answers Nick and Eyn find could have reverberations far beyond one family's happiness... to the fate of all humanity.
