Emma Healy has never fit in with the rest of her family. She's grown used to being the only ordinary one among her rather extraordinary parents and siblings. But when she finds a birth certificate for a twin brother she never knew she had, along with a death certificate dated just two days later, she feels like a part of her has been justified in never feeling quite whole. Suddenly it seems important to visit his grave, to set off in search of her missing half. When her next-door neighbor Peter Finnegan -- who has a quiet affinity for maps and a desperate wish to escape their small town -- ends up coming along for the ride, Emma thinks they can't possibly have anything in common. But as they head from upstate New York toward North Carolina, driving a beat-up and technically stolen car and picking up a stray dog along the way, they find themselves learning more and more about each other. Neither is exactly sure what they're looking for, but with each passing mile, each new day of this journey, they seem to be getting much closer to finding it.