Historian Doris Kearns Goodwin talks about the suffering of the house at Sappony, aka the Roanoke House. We see for ourselves the historic story of Edward Philippe Mott, a Philadelphia eccentric, who purchased the house and grounds as a retreat. He filled it with artwork, and insisted the Shakers building the house craft underground tunnels through the woods as well. Tragic accidents befell the builders throughout. He left a wife and daughter behind to live in the mansion with his male black lover, Guinness.
Obsessed with the art itself, he was quickly intimidated when The Butcher slashed all the paintings. A household servant claims she saw invaders from the woods, but Edward does not believe them. He locks much of the household staff naked in the root cellar until they confess. He dismisses his lover, a slave, in fury. He awakes to the villagers setting up outside, and he is dragged to his impalement and immolation outside. Guinness was able to escape, and was jailed, but did not tell about the trapped servants. They were found years later as the house passes through centuries of Mott descendants until Dandy Mott, the last of them, dies in 1952.
In 2014, Matt calls for the police to address the mob outside. Ambrose calls one last time for the family to surrender. Shelby plans a hasty escape with Flora, but a skittering creature steals the child first. They are able to recover her, but the past victims corral them. Edward materializes and leads them to safety through the tunnels. They emerge outside, and are captured and blindfolded by the Polk family.
Elias is there, kept alive but dismembered. He is concious enough to warn Matt that the "Mama" of the Polks took his leg. Mama Polk offers jerky to the Millers, but when she tastes it for herself finds the meat rancid. She blames the spoiled flesh on Elias' rot, and they bash his head in. Mama Polk explains that they've had a deal with The Butcher for 200 years. They have a symbiotic relationship, and the Polks are left in peace with their cannabis crop in exchange for sacrifices and bloody consecrations. The Polks, still upset about the police taking custody of the feral boys, plan to hand the Millers back to The Butcher. Matt takes an opportunity for them to escape from the Polk's truck, killing one of the brothers in the process. Mama Polk hobbles Shelby, all but severing her foot, in retaliation.
Lee testifies about her interrogation, as Shelby implicated her in Mason's death. They eventually released her for lack of evidence, and she gets a ride back.
The surviving Polks deliver the Millers to the mob at the house, where The Butcher offers condolences to Mama Polk. The colonists are to kill Flora and Ambrose attacks his mother instead, pulling them both into a pyre. Lee's timely arrival and Edward's hasty intervention allow the family to escape in a car.
They clean up and rest in a cheap motel after Shelby gets medical attention, and Shelby closes her testimonial with a mention that her nightmares continue.