When Charlie falls off a stepping stone in the woods, her whole world suddenly changes She stumbles in the 21st century, and picks herself up in the middle of the 20th! There are no trainers, no mobile phones - and she's a pupil at a weird outdoor school where the classrooms don't even have walls Somehow, Charlie has slipped through a nick of time Can new friend Jack help her find a way back - or will she be trapped in the past?