Found washed up on the banks of a remote loch, a mysterious girl is taken into the care of a psychiatric home in the Highlands of Scotland. Mute and covered in bruises, she has no memory of who she is or how she got there. The only clue to her identity is the Danish lullaby she sings. Inside the care home, she should be safe. But, harassed by the media and treated as a nuisance by under-pressure staff, she finds the home is far from a haven. And as her memories slowly surface, the Lullaby Girl does her best to submerge them again. Some things are too terrible to remember . . . but unless she confronts her fear, how can she find out who she really is?