Destroying Avalon — Kate McCaffrey

When Avalon moves to the city her life is turned upside down. Starting at a new high school, she finds herself at the center of a brutal cyber-bullying campaign. Inundated with obscene text messages, subject to increasingly vicious web site postings, and feeling miserable and isolated, Avalon relies on a small group of new friends. But as the threats escalate, she wonders if anyone is safe.