Twelve-year-old James Gregg and his friend Cady Walker survived the first leg of their families' journey west, after braving the wild rapids and encounters with Indians. But when James's father falls ill, the wagon train leaves both families behind to fend for themselves on the plains. James and his older brother, Jeremy, must protect everyone. But the two boys have been feuding since the trip began-and they continue to fight even as their food and...