Sixteen-year-old Odile vies for a coveted seat on an elite council that decides who may cross her town's heavily guarded borders.

To the east, the town is twenty years ahead in time. To the west, it's twenty years behind. The towns repeat in an endless sequence across the wilderness.

When Odile recognizes two visitors she wasn't supposed to see, she realizes that the parents of her friend Edme have been escorted across the border from the future, on a mourning tour, to view their son while he's still alive in Odile's present. Edme-who is brilliant, funny, and the only person to truly know Odile is going to die. Sworn to secrecy to preserve the timeline, Odile now becomes the top candidate.

Yet she finds herself drawing closer to the doomed boy, jeopardizing the future and her place in it.