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 they seem like one person, 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.