At the height of a swelteringly hot summer in Pawhuska, Oklahoma, Beverly Weston hires a young Native American woman named Johnna Monevata as a live-in housekeeper. Interviewing her in his disarrayed study, he explains that his and his wife Violet’s addictions—to alcohol and pills, respectively—have become so demanding that they can no longer handle simple errands or household tasks on their own. Moreover, he says, Violet has recently been diagnosed with cancer of the mouth. Beverly tells Johnna he’d understand if she didn’t want to take the job, but Johnna insists she needs the work. Beverly gives Johnna a volume of T.S. Eliot’s poems and tells her she should read it for her own enjoyment.
About a week later, Beverly has gone missing. Violet’s sister and brother-in-law, Mattie Fae and Charlie Aiken, have arrived in Pawhuska from their home an hour and a half away to keep Violet company. Also present is one of Violet’s three daughters, Ivy, who lives nearby. Ivy has called her sisters, Barbara and Karen, to let them know the situation. Violet pops pills while she waits anxiously for her daughters to show up.
Barbara arrives with her husband Bill and her daughter Jean. Barbara is miserable to be home, though it is clear that things are not great for her back in Boulder, either—she and Bill are fighting, and their fourteen-year-old child is emotionally distant and “hooked” on cigarettes. As Violet fills Barbara and Bill in on the circumstances of Beverly’s disappearance, she seems overly concerned about the state of his will and the valuables he left behind in a safe deposit box at the bank—a box, she tells Barbara and Bill, she has already emptied as per an “agreement” she and Beverly made some time ago. As Violet speaks, Barbara can see that her mother is high—Barbara warns Violet calmly that she will not go through “this” again.
Upstairs in the attic, where Johnna has been living, Jean asks Johnna’s permission to smoke pot in her room. Jean feigns interest in learning about Johnna’s past and traditions, but is really more concerned with her own problems. That night, as Bill and Barbara make up their bed in the living room, they have an argument about Bill’s infidelity; he has been having an affair with a younger student. Bill tries to calm Barbara down, begging her to save the fight for after Beverly comes back. Barbara resignedly tells Bill that her father is dead, and then goes to sleep.
A few hours later, Johnna wakes Barbara and Bill—the sheriff has arrived. They greet the sheriff, whom Barbara recognizes as her former high school classmate Deon Gilbeau. Gilbeau reveals that Beverly’s corpse has been found in a nearby lake, and tells Barbara she needs to come identify the body. As Barbara dresses upstairs, Violet enters the living room where the sheriff is waiting and puts on an Eric Clapton record. She babbles unintelligibly and dances erratically to “Lay Down, Sally.”
Some days later, after Beverly’s memorial service, the entire family is preparing for a funeral dinner. Barbara and Ivy’s sister Karen has arrived—with a new beau in tow—and will not stop rambling to Barbara about how wonderful her life has become. Upstairs, Ivy, Violet, and Mattie Fae look through boxes of old pictures. Violet needles Ivy about her frumpy appearance and urges her to start dressing more femininely if she wants to attract a man. Ivy reveals that she already has a man but will not tell her mother or her aunt who it is she’s seeing.
Downstairs, Bill, Jean, and Karen’s shady fiancé Steve return from a grocery run. Steve teases Jean, telling her that she smells like marijuana. When she denies using the drug, Steve tells her it’s a shame she doesn’t partake—if she did, he’d “hook [her] up” with some “tasty shit.” Jean immediately caves, begging Steve to help her get “fucked up,” and Steve tells her that later, he will.
Charlie arrives at the house with his and Mattie Fae’s adult son, Little Charles, who slept through the funeral. Little Charles is distressed at having missed the service and worries that his family, who already makes fun of him incessantly, will be furious. Charlie tenderly reassures Little Charles that he is loved and urges him to give the rest of the family a chance to see the real him. Charlie goes into the house, and Ivy meets Little Charles out on the porch. The two share a kiss, and it becomes clear that they are having an affair.
Dinner is served, and almost immediately the bickering begins as Violet cooks up discord with nearly every member of the family. When Barbara accuses Violet of attacking her entire family one by one, Violet becomes enraged, and insists it is time that their family told some truths. Barbara tells Violet that she’s a drug addict, and Violet joyfully admits to the accusation. She holds her bottle of pills aloft and announces to her family that if any one of them tries to take the pills from her, she will eat them alive. Barbara lunges for Violet and, after a struggle, successfully wrestles the pills away from her. Barbara orders her sisters to search the house for Violet’s stashes of pills. Violet cries and tells Barbara that she’s out of line—this is Violet’s house. Barbara towers over her mother and screams in her face: “I’m running things now!”
Later that night, Barbara, Karen, and Ivy sit upstairs, discussing what to do with their mother. After the explosive dinner, they took her to see her doctor, who has been overprescribing her medication for a long time now—Barbara and Ivy know, though, that Violet sees multiple doctors and manipulates them all into writing her potentially dangerous prescriptions. Barbara asks Ivy if there is something going on between her and Little Charles and warns her not to try and have children with him. Ivy reveals that she can’t bear children, anyway—she had a hysterectomy last year after she was diagnosed with cervical cancer. Barbara and Karen are shocked by this news, and Barbara asks Ivy why she wouldn’t have told her sisters she was struggling with cancer. Ivy says that she feels no connection to either of her sisters, or to anyone in her family except Little Charles. Ivy then reveals that she and Little Charles are planning on running away to New York together; Ivy is tired of the burden of caring for her abusive, addict parents.
Violet enters the room, sober but shaky, and apologizes to the girls for being so mean. Barbara asks for a moment alone with Violet, and the two call a truce. Downstairs, Ivy finds Little Charles watching TV in the living room. He brings Ivy over to the piano, where he plays a love song he’s written for her. Mattie Fae and Charlie come into the room, interrupting them, and Mattie Fae tells Little Charles that it’s time to leave. Seeing that the TV is on, Mattie Fae begins berating Little Charles for his obsession with television. Charlie orders Little Charles and Ivy to leave the room. As Charlie, alone with Mattie Fae, warns her that if she cannot find room in her heart to be kind to her son, he will leave her, Barbara—who has come downstairs—listens in the doorway. When Charlie goes outside, Mattie Fae becomes aware of Barbara’s presence.
Barbara apologizes for eavesdropping, and Mattie Fae asks if something is going on between Little Charles and Ivy. When Barbara admits that there is, Mattie Fae says that such an affair can’t happen—Little Charlies is not Ivy’s cousin, not her half-brother. Mattie Fae reveals that she had an affair with Beverly many years ago, and that Little Charles is Beverly’s son, not Charlie’s. Now that Beverly is dead, Mattie Fae says, she—and Barbara—are the only ones who know the truth. Mattie Fae begs Barbara to put a stop to whatever is happening between Ivy and Little Charles; after all, Barbara said she was the one “running things.”
Later that night, Jean and Steve are sneaking around the house, smoking pot and giggling. Steve begins groping Jean. Johnna appears with a cast-iron skillet in her hand and starts beating Steve. The whole house awakes to the commotion, and Karen takes the injured Steve into the next room, where they begin packing their things to leave. Barbara and Bill ask Jean what happened and attempt to get her to tell them the truth, but she will not—she accuses her parents of being unable to tell right from wrong themselves anymore, and of using her to do that work for them. Barbara attempts to talk to Karen, but Karen will not let Barbara get a word in. Karen asks Barbara to get the truth from Jean—Karen does not want to believe that Jean is “blameless” in what happened. Karen then announces that she is returning to Florida with Steve.
After Karen leaves, Bill comes downstairs with his and Jean’s suitcases. He is taking Jean back to Boulder. Barbara asks Bill if they will be able to repair their marriage, and Bill says they won’t. Later, in the early hours of the morning, Barbara and Johnna sit up in the study. Barbara drinks a glass of whiskey and offers Johnna the chance to quit. Johnna insists she can do the job, and that she wants to stay.
The following morning, Sheriff Gilbeau comes by to talk to Barbara—he has received a call from the proprietor of a local motel who says that Beverly stayed there in the days between his disappearance and the recovery of his body. Sheriff Gilbeau is going to follow the lead and see if he can find any incoming or outgoing calls to Beverly’s motel room.
That night, Barbara and Ivy sit at the dinner table. Barbara tells Ivy she needs to break things off with Little Charles, but Ivy wants to do the opposite—to tell Violet about her affair. Violet comes down to dinner. As she, Ivy, and Barbara begin eating, Ivy tries to tell Violet the truth. Barbara keeps cutting her off, attempting to stop the secret from coming to light. Ivy keeps starting sentences with “Little Charles and I,” but can’t get any further than that—eventually, Violet finishes the sentence for her: “Little Charles and you,” she says, “are brother and sister.” Violet reveals that she has known the truth of Little Charles’s parentage all his life—Beverly knew that she knew, she says, but the two of them never discussed it.
Ivy, shocked and horrified, leaves, calling both Barbara and Violet “monsters.” Violet continues talking to Barbara about Beverly and Little Charles, and suspects that in the end Beverly ultimately killed himself because of his guilt over the situation. If she had been able to reach Beverly at the motel, Violet says, she would have told him to forget his guilt and come back home. Barbara is stunned to realize that her mother knew where her father was after he disappeared all along. Violet reveals that Beverly left a note when he left Saturday morning, saying he could be reached at the Country Squire Motel. Despite this fact, Violet waited until Monday—after the bank opened and she had emptied out the safe deposit box—to try calling Beverly, by which point he’d already checked out of the motel.
Realizing that her mother could have prevented her father’s death, but chose his money over his salvation, Barbara leaves. Violet, disoriented and seemingly high once again, puts “Lay Down, Sally” on and dances about the living room before attacking the record player and destroying it. She calls for her daughters, and when they don’t answer, she begins calling for Johnna. She crawls up the stairs to Johnna’s room, and places her head in Johnna’s lap. Johnna comforts Violet and repeats out loud a line of T.S. Eliot’s: “This is the way the world ends.”