1978. For over twenty years, Mrs. Medlock has guarded the secrets of Marwood Manor - secrets that poisoned the atmosphere of the house and irrevocably altered its inhabitants. One of the few remaining servants, she remains to protects a dying aristocratic order, caring for the Lord and Lady's reclusive young son. Until Mary, a distant relative, arrives seeking refuge and determined to uncover the manor's sinister past. As Mary's curiosity draws her ever closer to the truth, the insidious rot spreads - and a deadly history threatens to overwhelm them all.