In 1948, Irene Willard, who’s had five previous miscarriages in a quest to give her beloved husband the child he desperately desires and is now pregnant again, comes to an isolated house-cum-hospital in the Berkshires, run by a husband-and-wife team of doctors who are pioneering a cure for her condition. Warily, she enlists herself in the efforts of the Doctors Hall to “rectify the maternal environment,” both physical and psychological. In the meantime, she also discovers a long-forgotten walled garden on the spacious grounds, a place imbued with its own powers and pulls. As the doctors’ plans begin to crumble, Irene and her fellow patients make a desperate bid to harness the power of the garden for themselves --- and must face the incalculable risks associated with such incalculable rewards.

At their newly founded school, Samuel Hood and his daughter, Caroline, promise a groundbreaking education for young women. But Caroline has grave misgivings. After all, her own unconventional education has left her unmarriageable and isolated, unsuited to the narrow roles afforded women in 19th-century New England. When a mysterious flock of red birds descends on the town, Caroline alone seems to find them unsettling. It's not long, though, before the assembled students begin to manifest bizarre symptoms: rashes, seizures, headaches, verbal tics, night wanderings. Fearing ruin for the school, Samuel overrules Caroline's pleas to inform the girls' parents and turns instead to a noted physician, a man whose sinister ministrations --- based on a shocking historic treatment --- horrify Caroline.