Grace put out her hand, almost touching the mirror. Her image did the same. 'There's another world in there.' 'We could float in and out of it.' Deep in a Derbyshire valley live two girls, twins, so alike that even their family can't tell them apart. But tragedy is waiting. When the valley is sold to be flooded for a huge dam, the villagers are forced to leave their homes. Deep secrets are uncovered. New characters enter their lives and desires, love and grief come to the surface.