In an edenic community of wealthy Bay Area families, Molly Nicholl, a replacement teacher from a poorer, scrubbier version of California, arrives in the middle of the school year and soon becomes intrigues by the hidden lives of her privileged students. Unknown to her, a tragedy from their middle school years continues to reverberate for 'her' kids. Among these are Callista, a hippie outcast who hides her intelligence for reasons of her own; Ryan the star pitcher and sex object; Dave, the nice kid whose parents' obsession with his SAT scores threatens to upend his life; Emma, a dancer who balances her dreams of bright stagelights with wildness on the weekends, and Nick, the uneasy kingpin of schemes, pranks, and parties. These teens are all navigating in a world in which every action may become public--postable, shareable, indelible--a world Molly finds both alluring and dangerous.