Meanwhile, Sarah’s cousin, Abigail (Emma Stone) arrives to The Queen’s estate via carriage. She is shoved by another rider on the way out and falls into filth, and when she enters the castle, the maids play a trick on her and send her to meet her cousin smelling atrocious. Abigail’s father has fallen from grace onto extremely hard times and Abigail is desperate for a job. Unimpressed, Sarah gets her a job in the downstairs, where she shares a room with all the other maids. The other maids bully her, even tricking her into touching lye with her bare hands, burning her.
Robert Harley (Nicholas Hoult), a politician, is desperate to stop the war. But Sidney Godolphin (James Smith) argues the opposite to The Queen, insisting the fight must continue. Sarah, the one with the most power to influence Anne’s opinion, convinces Anne to double the tax on the citizens to pay for the new phase of the war, and Harley is furious.
One night, Anne has an extremely terrible case of gout and is screaming in pain. Abigail steals a horse and goes out into the forest, picking herbs to ease Anne’s pain. While there, she makes eye contact with the handsome Samuel Masham (Joe Alwyn) but plays coy. She lies her way into Anne’s chamber to apply her remedy, but Sarah catches her and orders her to be lashed however, when the remedy works, Sarah stops the lashing after only a few hits and speaks with Abigail. She’s impressed, and takes on Abigail as her assistant. With this promotion, Abigail gets her own room away from the other maids. Abigail reveals that previously, her father had lost her in a bet to an old German man who she was forced to be with, and she will do anything to get out of that life. Abigail also coughs loudly in front of Anne, making sure to explain she caught a cold from picking her healing herbs.
At a grand party, Harley tries to talk with Anne about not continuing the war, but can never get her out from under Sarah, while at the same time, Abigail sneaks into Anne’s chambers to take books. When Sarah has a dance with Masham, Anne grows agitated and demands Sarah take her back to her chambers. She slaps Sarah, angrily, who apologizes. They enter Anne’s chamber and begin to have sex, to the shock of Abigail, who flees without being seen.
John (Mark Gatiss), Sarah’s husband, leaves to lead the ongoing battle in the war. Sarah is worried but resolved. Over a round of shooting, Abigail asks Sarah how she can be alright with her husband being in such grave danger. Sarah explains that she believes this is what is best for the country and she has prepared herself to pay the price she notes that Abigail understands this, having given herself over to the German.
Harley approaches Abigail and asks her to spy on Sarah and Anne and bring him anything he can to help him curry favor with the Queen. Abigail declares she’ll do no such thing and tells Sarah about it, who is unfazed. Sarah becomes busy with matters of state and making decisions, and sends Abigail to socialize with and watch after Anne. Although Anne at first is not interested in Abigail, Abigail bonds with her by asking about her rabbits. She has seventeen, one for every child she’s lost. Anne softens to Abigail, and spends more and more time with her. One evening, Sarah enters Anne’s chambers and finds Abigail naked in bed with Anne, sleeping after having slept together. Enraged, the next day she hurls books at Abigail, accusing her of being a schemer, and fires her outright from Anne’s service. Abigail, shaken, takes a book and bashes herself in the face with it until her nose is bloody, then waits outside Anne’s chambers and cries.
The next day, Sarah sees Abigail still in Anne’s employ. Queen Anne tells Sarah she is not fired because she likes having her around… and likes sleeping with her. The three travel together awkwardly. Sarah takes Anne aside and tells her that enough is enough, she’s made her point but Anne confesses she likes having everyone vying for her affection.
Sensing Sarah and Anne’s not-wavering bond, Abigail meets with Harley, and agrees to help him, in exchange for a favor. She wants to marry Masham, who she has had a continuous flirtation with. Harley knows she can never do that, because she’s not a Lady. He promises to make it happen, and Abigail tells him at parliament the Queen is going to double the tax, and promises to get him meetings with Anne unaccompanied by Sarah. With that information, he is able to ambush her before her speech, he gives a rousing speech thanking her for not cutting the tax and ending the war, and the room cheers. Pressured by that, Anne faints, unsure of what else to do. Sarah knows someone must have gotten to Harley and set them up.
Abigail gets more herbs from the garden and poisons Sarah’s tea. Sarah then goes out for a horseback ride, and when the poison takes affect, she passes out and is dragged violently by her horse out into the country. The whole estate is concerned about Sarah’s disappearance, but Anne suspects she might be faking it for attention, jealous of her getting close to Abigail. Sarah is found bruised, bloodied and unconscious outside of a brothel.
With Sarah gone, Anne is easily influenced. Harley lets her in on the fact that Abigail and Masham have been romancing one another, and Anne insists they be married. In order to make that happen, she makes Abigail a Lady. Abigail and Masham are married. Then, together, Abigail and Harley also weaken Anne’s resolve on the issue of the war. Queen Anne also begins to worry that something serious may have happened to Sarah.
Sarah awakens in the brothel, a massive scar on her cheek from her injuries. She demands to be released, and initially they refuse but she sends word to her contacts to bring money and is released. When she returns, she is appalled to see Abigail is now a lady. She slaps her across the face and then returns to her chambers and finds old letters from Queen Anne. She goes to Anne and tells her that she needs to continue the war, double the tax, and remove Abigail from her service and move her away from them. Anne balks, and Sarah tells Anne if she doesn’t she will release her love letters that she wrote to Sarah to the press, causing a huge scandal. Anne is deeply betrayed.
Feeling guilty for threatening Anne, Sarah burns the letters however she is quickly informed that she needs to return her keys to Anne’s chambers and that she is being removed from the castle. Sarah goes to outside Anne’s door and apologizes, explaining she burned the letters, but Anne doesn’t acknowledge her. Sarah moves to a different estate. With Sarah gone, Abigail has free reign, and spends her days partying with the high class and reluctantly tending to Anne.
Anne is beginning to falter on the issue of the war with Harley and Abigail constantly influencing her. Sidney wonders if Sarah would have a different opinion, but Anne balks. When he brings up the idea of Sarah sending her an apology, Anne seems interested in the idea although acts like it doesn’t matter to her. Sidney goes to Sarah and convinces her to mend fences with Anne and write her a letter. Sensing Anne’s pining for Sarah, Abigail lies and tells her that she’s looked at the books and it seems that Sarah and John were stealing from her. Anne absolutely doesn’t believe her. Anne gets more and more upset waiting for the letter from Sarah. It finally arrives at the estate, but Abigail intercepts it and burns it. Later, Harley is trying to convince Anne to remove John from the military. Sidney is aghast, since John just won for them. But Anne declares that John has been stealing from them and orders him removed and the war ended. She insists that John and Sarah be banished. Sarah and John are at home when troops arrive outside their place and Sarah seems them out the window.
As Anne sleeps in her chambers, Abigail steps on one of the rabbits, pressing down on it with her foot. Anne stirs and she lets the rabbit go. Anne then orders her to come take care of her, and Abigail, subservient again, rubs the queens legs as the rabbits move around.