Flash of Red (Celia's Journey, Book 3)

After what happened at school last year, Celia Fincastle is looking over her shoulder, wondering what might happen next. She's convinced people are following her - at Aunt Agatha's, at camp, even at school - but no one believes her, not even her advisors. Celia's friends tell her she's imagining things, but once they're on their class trip, they soon learn that everything can change in a flash.