When Essa meets Oliver - a brainy indoor type, in Boulder, Colorado for the summer - she is cautious at first, distrustful of the tourist crowd and suspicious of Oliver's mysterious past in Chicago. But her nine-year old sister Puck is charmed and pushes Essa toward him. Soon Essa finds herself showing Oliver the Boulder she has forgotten. After spending a night stuck in a mountain storm, Essa wakes to find Puck missing. Now Essa must rely on her newfound spiritual strength if she is to save her sister's life, and ultimately her own.