When Shelby Black boards the bus for the last field trip of the year, her biggest worries are not having friends to sit with and figuring out how to convince her father to let her go live with her mom. An accident never enters her mind. After waking in the desert to find she's one of three people still on the bus, she must work to solve the mystery of the other missing students and why she was left behind. There are other strange things happening, too. Why does time seem to act differently in the desert? Why can't she feel hunger or pain when the others can? Where did the large, black wolf that's been watching them come from and is it stalking or protecting them? Shelby's worries from before the wreck don't seem as important as her new biggest fears. Will she live out the day and will she ever find a way home?