In the small village of Saveock Water in Cornwall live the Burnett siblings. Parentless, they keep to themselves and make their own way. For some reason, though, the older girls keep the younger two under close watch, locking their door at night. The youngest, Lillian, thinks they're plotting against her. Lillian's mind is already unstable when she meets Davy Polglaze. Committed to St Lawrence's Mental Asylum, she plans her escape, but with rapid...