Nina Winchester

Nina welcomes Millie warmly, then treats her like an enemy the next day. She wrecks what the maid tidies, denies orders she gave and makes scenes in front of the other neighborhood moms. She says she's pregnant, even though she has premature ovarian insufficiency.

The neighbors tell Millie that Nina was once institutionalized. She was accused of trying to drown Cece as a baby, and her parents died in a suspicious house fire. Evelyn, her mother-in-law, makes no secret of her contempt either. To Millie, the explanation seems simple: her boss is unstable and dangerous.

Nina buys Broadway tickets, then denies it. When she learns about Andrew and Millie's affair, she threatens the maid. All of it had a purpose.

The letter Nina leaves reveals the truth. Andrew had abused her for years: he locked her in the attic, forced her to pull out her own hair and framed her for the drowning so no one would believe her. Nina once planned an escape with help from Enzo, the groundskeeper, and it failed. So she picked a maid with a criminal record, counting on Andrew to take an interest and on Millie to fight back.

Nina leaves the house with Cece. It's her daughter who insists they go back to check on Millie. Nina climbs to the attic to free her, and Andrew attacks them both. Millie pushes him down the stairs, and he dies.

Nina drops a lightbulb beside the body, as if Andrew had fallen while changing it. When the police arrive, the two women tell the same story. Officer Connors asks too many questions, but she ends up accepting the accident.

At the funeral, Evelyn, Andrew's mother, notices her son's missing teeth. The mourners are left confused. Afterward, she hands Millie a $100,000 check and leaves with Cece to start over.

Before stepping out of Millie's life, Nina refers her to Lisa, a friend who shows signs of living through the same hell. Nina knows Millie is the right person for that kind of job, and so does Millie. The maid she used as a weapon becomes an ally.

In Freida McFadden's book, Nina gains weight on purpose to make herself less attractive to Andrew and has a romance with Enzo, the groundskeeper. Amanda Seyfried, who plays Nina in the movie, received an executive producer credit.