Julia Robinson and Cassie Burnes have been friends since nursery school. They have shared everything, including their desire to escape the stifling limitations of their birthplace, the quiet town of Royston, Massachusetts. But as the two girls enter adolescence, their paths diverge: while Julia comes from a stable, happy, middle-class family, Cassie never knew her father, who died when she was an infant, and has an increasingly tempestuous relationship with her single mother, Bev. When Bev becomes involved with the mysterious Anders Shute, Cassie feels cruelly abandoned. Disturbed, angry and desperate for answers, she sets out on a journey that will put her own life in danger, and shatter her oldest friendship.