In early 18th century England, Queen Anne's reign is marked by her frail health and mercurial temperament. With England at war with France, political maneuvering is the sport of the court, and the Queen's close friend, Lady Sarah Churchill, Duchess of Marlborough, effectively rules the country through her influence over the Queen. Lady Sarah's control is exercised with a combination of manipulation and genuine affection, ensuring that the Queen's eccentric behavior does not impede the governance of the state. The war with France is draining the country's resources, and the leadership must navigate an increasingly strained relationship with a frustrated and suffering populace.

The tightly-woven fabric of court life begins to unravel with the arrival of Abigail Hill, a fallen woman of noble birth seeking employment and protection. She quickly ingratiates herself into service and catches the eye of Sarah, who takes her under her wing. However, Abigail proves to be more than just an innocent servant—she is ambitious and cunning, recognizing the opportunity to restore her social status by gaining the Queen's favor. Through a mix of tenderness and scheming, she begins to fill the emotional gaps in the Queen's life, challenging Sarah's privileged position. The royal court becomes a battleground for influence, as both cousins employ whatever means necessary to become the Queen's "favourite.