Nia would do anything to win the approval of her boyfriend Scott and his friends, especially mean girl Olivia. Olivia dares Nia to explore an abandoned prison. Facing dark tunnels, distant noises and creepy mementoes left behind by incarcerated criminals will surely all be worth it to finally become part of the group. But it isn't long before Nia and her little sister, Kayla, find themselves trapped inside.

And then Kayla vanishes.

Suddenly, this feels like more than a game gone wrong. There is a horrifying secret hidden within the prison's walls - and now someone is hellbent on making sure Nia and her little sister become its last inmates...

An utterly compelling take on toxic friendship from a remarkable UK debut author.