Young Tate is playing in the Murder House when the door to the cellar opens, seemingly on its own. He shoves his toy truck down the stairs and then goes to get it. After some searching, he finally finds it beneath a table. When he goes to get it, the ghost of Thaddeus Montgomery grabs him and starts to pull him into the darkness. However, Nora arrives and orders Thaddeus away, and pulls Young Tate to safely. She tells the boy that if Thaddeus ever comes to him again, Tate should just close his eyes and tell it to go away. Tate says that he wishes Nora was his mother as he cries, and Nora tells him to dry his tears because life is too short for sorrow.
Tate finds his childhood toy truck and hears Nora crying. He goes to find her but she doesn’t remember him, even when Tate recites her own words about how life is too short for sorrow. Nora wonders where the baby she was promised is to be found, and Tate says that she can’t have Vivien’s child because Tate is in love with the twin’s sister, Violet. Nora refuses to accept that and says that she’ll take the baby.
Ben takes Violet out of the house and insists that she should go with him to get Vivien. When Violet says that she feels sick, Ben tells her to lie down in the back. She does but when Ben drives away from the house, Violet disappears and finds herself back in her room. Tate is trying to look up Youtube and Violet wonders what the future will be like and how it will pass them by because they will never change. They hear Chad and Patrick decorating the nursery and go to investigate. Chad says that they’ll finally have the children they always wanted but Violet warns him that Ben is taking Violet away. Unimpressed, Chad says that there’s nothing Violet can do to stop them, and that he and Patrick will have their child.
Later, Constance visits the Murder House and Violet warns her about what Chad and Patrick intend. The girl asks to speak to Billie Dean and see if she knows a way to get rid of ghosts. Constance agrees to contact Billie Dean and then goes to the nursery. As she admires the cribs, Chad comes in and tells her to stay away. Constance says that he and Patrick are abominations, not fit to be fathers, and that being a birth mother is the important thing. Chad points out that the ghosts of her children occupy the house and ignores her insults, and Constance offers him Ben’s child rather than the other twin, the one that is her grandson by Tate. Chad doesn’t want to negotiate, and explains that they plan to kill the babies when they reach the perfect age of a year and a half so that they will remain that way forever.
Constance brings Billie Dean to the house and the medium scans the house. She quickly realizes that Violet is a ghost and the girl asks her not to tell the others. Billie Dean then explains that a strong electromagnetic force can dispel psychic energy, but that the force that pervades the house is using the spirits as conduits so it can move in the outside world. Tate appears and offers to help, but Billie Dean says that he’s helped enough. Constance tells her son to leave and he does, and Violet wonders what is going on. Tate’s mother lies and claims that Tate’s spirit influenced Billie Dean.
At the hospital, Ben is checking out Vivien, who wonders why Violet isn’t there. Dr. Marchesi comes in and repeats his advice that she shouldn’t travel until after she delivers. Vivien insists that she is going to Florida to be with her sister, Jo, and Marchesi warns her that the obstetrician in Florida will need to perform a C-section. When Ben wonders what he means, Marchesi explains that one twin is developing at an accelerated by feeding on the nutrients that would go to the other twin. Ben is shocked at the news and Vivien admits that she was waiting to tell him until they got to Florida.
Billie Dean tells Constance and Violet of how in 1590, the Roanoke colonists died mysteriously and their spirit continued to haunt the area, killing the local Indians. Finally the tribal elder used their personal belongings to summon them to a great fire and then uttered a single word of banishment, “Croatoan.”
Later, Violet goes to see Tate in her room and tells him that they have to get a personal possession from both Chad and Patrick so that they can banish them. Tate is more concerned about Billie Dean and why she told him to go, and wonders if he did something bad. Violet tells him to focus and Tate goes to the nursery room. Despite the fact that he killed him over a decade ago, Tate flirts with Patrick, offering his body and suggesting they let bygones be bygones. Patrick beats him instead, enjoying the fact that Tate will keep healing so that he can beat him again. As he continues hitting the teenager, Patrick says that it wasn’t supposed to be like this, and that he had fallen in love with someone else and was going to leave Chad. Chad is at the door and hears Patrick’s confession, and storms off. Patrick goes after him while Chad manages to slip the engagement ring from his tormentor’s finger.
Ben and Vivien drive back to the house to pick up Violet. While Ben goes in to get his daughter, Vivien waits in the car only to go into labor.
Violet meets Tate in her bedroom and shows him that she obtained Chad’s wristwatch. Ben arrives and pounds on the door, saying that they have to go. Violet insists that she has to stay while her parent leave without her, but Ben grabs her and hauls her downstairs. He wonders if she’s using drugs and Violet finally tells him that she’s dead and trapped in the house.
Constance hears Vivien’s pains and comes to help her. She takes Vivien into the house where they meet Ben and Violet. Constance warns that they don’t have enough time to get Vivien to the hospital and ushers Vivien to the living room. The baby is already crowning and Ben goes to call Dr. Hall while Violet tells Constance that they’re not safe. Constance tells the girl that she knows what she has to do.
Ben tries to call out but discovers that the phone lines are dead. He looks out the window at the car and sees the twins smashing the windows and spiking the tires. The power goes out and Constance tells Ben that it’s time. They go to the living room where Dr. Montgomery has arrived with Gladys and Maria as his nurses. Ben starts to black out but Constance slaps him and then explains that the house is doing what it can to help. While Ben goes to Vivien’s side, Dr. Montgomery orders ether for Vivien to dull the pain. Vivien worries that Ben will leave her but he assures her that he’ll always be there for her. As he remembers Violet’s birth, Vivien gives birth to the first twin but Dr. Montgomery confirms that it is still born. He takes it to Nora while Constance tells Vivien that the other twin is ready.
Violet goes to the basement and throws the ring and the wristwatch into the furnace. Chad appears and Violet says “Croatoan.” He moans in pain for a few seconds, and then bursts into laughter and admits that he’s kidding. When Violet wonders why the curse didn’t work, Chad explains that it’s all just made-up bullshit by people who want to feel in control. However, he then tosses the broken cribs into the furnace and tells Violet that her new brothers are safe. Heartbroken, Chad admits that he is now cursed to spend eternity with a man who doesn’t love him. He says that Tate does love Violet, but that he’ll always be a monster. When Violet defends her boyfriend, saying that Tate doesn’t remember what he did, Chad tells her that Tate raped Vivien.
Dr. Montgomery uses forceps to manipulate the second twin and bring it out safely. Violet arrives and apologizes to her mother for not visiting her, while Ben tells Vivien to concentrate. He insists that they can be happy together like they were before. Vivien gives birth to the second twin and Constance takes it to be washed. Meanwhile, Ben asks Dr. Montgomery if Vivien will be okay but he has no assurances for him.
In the kitchen, Constance is tending to the baby when Moira comes in. The housekeeper cries at the sight of the baby, but then both women turn as Hayden comes in and tells them to hand over her body.
When it’s clear that Vivien is dying, Violet tells her to let go and come to the other side with her. Vivien says that she doesn’t have a choice and died despite Ben’s pleas for her to stay with him. As he stares at his wife’s corpse in shock, Dr. Montgomery and the other ghosts disappear.
Violet goes to her room to find Tate. She tells him that Vivien is dead and demands to know why he sought counseling with Ben. Tate finally admits to her that he knew he was dead and claims he can only remember that the police shot him dead. However, Violet doesn’t believe him and demands the truth, asking why the police shot him. When Tate feigns amnesia, Violet tells him that he killed kids, including the four that sought him out on Halloween. As Tate breaks down into tears, Violet asks him why he killed, Chad and Patrick, and raped Vivien. The boy says that he was different then, but Violet says that he’s not just attracted to the darkness, but is darkness. She refuses to forgive him and says that he has to pay for killing Vivien. Tate begs her to stop but Violet closes her eyes and tells him to go away. When she opens her eyes, Tate is gone. As Violet cries, her mother appears to her and holds her, saying that she was very brave. When Violet apologizes for Vivien losing her baby, Vivien says that she didn’t and holds her daughter tight.