In 1708, Britain is at war with France, and Queen Anne sits on the throne. In frail health due to gout, Anne shows little interest in governing, instead preferring eccentric activities such as racing ducks and playing with her rabbits, which represent the seventeen children she has lost over the years. Her confidante, adviser and secret lover Sarah Churchill, the Duchess of Marlborough, effectively rules the country by the confidences she passes to the Queen. Sarah’s efforts to control Anne are undermined by Robert Harley, a member of Parliament and influential landowner responsible for bringing in state taxes for the war.
Meanwhile, Abigail Hill, Sarah’s impoverished younger cousin, arrives at Court in search of employment. Abigail’s history is tainted by her father, who has gambled away his good name and previously handed over his daughter to settle his debts to a German. Abigail is at first forced to do menial work as a scullery maid in the palace, but after seeing the Queen’s condition, she sees an opportunity to ingratiate herself with Sarah and, eventually, Queen Anne herself. She uses herbs to aid the Queen’s inflamed legs and though she is initially punished by Sarah for her presumption, the remedy eases the Queen’s suffering. In gratitude, Sarah makes Abigail her lady-inwaiting.
Harley soon approaches Abigail, hoping to use her as a spy in order to find out what Sarah’s schemes are and figure out a way to circumvent her authority. Abigail initially rebuffs him, but soon she becomes aware of the secret lesbian relationship between Anne and Sarah. As she is interested in the Queen’s homosexual inclination, Abigail begins planning her own ascent to win the Queen’s favour.
While Sarah is focused on the war effort, Abigail takes advantage of her preoccupation to kindle a friendship with Anne, which soon becomes a sexual relationship. Sarah soon becomes aware of Abigail’s machinations and attempts to have her sent away. Abigail spikes her tea, which later causes Sarah to fall off her horse and be dragged away into the forest, vanishing for several days. Queen Anne, thinking that Sarah has temporarily abandoned her in order to make her jealous, takes Abigail into her favour. Her first reward is to be allowed to accept the marriage proposal of Samuel Masham. Masham is a baron in Anne’s court and the marriage reinstates Abigail’s noble standing as a baroness.
A battered and scarred Sarah awakens in a bordello. When she returns to court, she issues an ultimatum to Anne: send Abigail away, or she will leak to the press the letters between Sarah and Anne that detail their sexual relationship. This threat backfires and destroys the relationship between Anne and Sarah. Even though Sarah voluntarily burns the letters in penance, she is ultimately stripped of her offices and sent away from court. When Abigail, now promoted to Keeper of the Privy Purse, presents what she claims to be evidence that Sarah had been embezzling money, Sarah and her husband are exiled from Britain.
Soon after Abigail’s victory, her ego and gluttony for luxury starts to inflate the same way Sarah’s had. One day while lounging in the Queen’s chamber Abigail abuses one of Anne’s rabbits, which she notices and immediately takes offense to. Anne promptly responds to Abigail’s abuse by grabbing Abigail’s hair and ordering her to massage her legs the way she would a servant. As Anne re-establishes her stature as Queen, Abigail and Anne both appear to have adjusted to the present state of affairs.