Outside London behind a stone wall stands Lake House, a private asylum for genteel women of a delicate nature. In the winter of 1859, recently-married Anna Palmer becomes its newest arrival, tricked by her husband into leaving her home, incarcerated against her will and declared hysterical and unhinged. With no doubts as to her sanity, Anna is convinced that she will be released as soon as she can tell her story. But Anna quickly learns that liberty...

New England, the 1890s. A man calling himself Doctor John Shepherd arrives at an isolated women's mental hospital to begin work as assistant to the owner Dr Morgan. As Shepherd struggles to conceal his own dark secrets, he finds the asylum has plenty of its own. Who is the woman who wanders the corridors by night with murderous intent? Why does the chief nurse hate him? And why is he not allowed to visit the hospital's top floor? Shocked by Morgan's...