Up and down the country, thousands of children have sleepovers every single day. Some stay with friends, some with family. But what happens when instead of going home, they vanish? Into thin air..

In the case of Tia Sharp, her mum said it was almost like she walked out the door and fell down a hole. But she was about to learn the truth was far, far more disturbing than that. More disturbing than anyone could EVER have imagined.