A secret from her past threatens to detonate her present... On her first day at a new school, Ruby finds a note in her locker saying I Know You Did It. She's terrified that someone has found out she was responsible for the death of a girl called Hannah in a playground when they were both toddlers - a secret she has been keeping guiltily for ten years. When other pupils at the school start suffering serious accidents, the finger of blame points at Ruby. She knows she's not the perpetrator, but who is? And what link do they have to her past...?