School should have been the safest place… For Lizzie Riley, switching her six-year-old son Tom to the local academy school marks a fresh start, post-divorce. With its excellent reputation, Lizzie knows it’ll be a safe space away from home. But there's something strange happening at school. Parents are forbidden from entering the grounds, and there are bars across the classroom windows. Why is Tom coming home exhausted, unable to remember his day? What are the strange marks on his arm? And why do the children seem afraid to talk? Lizzie is descending into every parent’s worst nightmare: her little boy is in danger. But will she be able to protect him before it’s too…