On a foggy evening in 1947, 17-year-old Eliza and her troubled little sister Rebecca are banished by their aunt and sent to work at an isolated Welsh mansion. But there are rumours of missing maidservants and a ghost that stalks the deserted halls ... Wandering through the mansion's dusty rooms, Eliza finds blood-spattered books, crumpled photographs and portraits of a mysterious woman – clues to a terrible past that might just become Eliza's future. As Eliza unravels a mystery that has endured for decades, Rebecca falls under the spell of cruel housekeeper Mrs Pollard, who will stop at nothing to keep the house's secrets. But can the sisters uncover the truth and escape back to London before they meet a dreadful fate?