An unnamed real estate agent and her client discuss the possible uses of the dining room in an old house available for sale. Although the client expresses some sentimental interest in the room, he declines to make an offer on the home, and the two plan to look elsewhere.

At a different time and place, the siblings Arthur and Sally argue over which of them will get the dining room table left behind by their widowed mother, who moved to Florida. The issue remains unresolved, and the Father, a precise, finicky man, starts complaining to Annie, the servant, that on the previous day he found a seed in his orange juice. He begins instructing his son and daughter in breakfast-table deportment and criticizes the deficiencies of his son’s teacher, Miss Kelly. The Father is joined by his wife, the Mother, while another husband, Howard, expresses irritation with his wife, Ellie, because she starts to do schoolwork on the dining room table. He complains that the table and its place mats, his family’s heirlooms, are very valuable, and he tries to persuade her to work elsewhere. When she resists he storms out and Ellie, unfazed, returns to her work on the table.

Carolyn, a young teenager, next explains to her unreceptive mother, Grace, why she wants to go to the theater with her aunt Martha. Grace, who believes that the eccentric, mildly bohemian Martha will be a bad influence on Carolyn, tries to make her daughter stay home to fulfill other obligations while insisting that Carolyn is free to make up her own mind. To Grace’s chagrin, Carolyn decides to go with her aunt.

A young boy, Michael, who is sick and at home from school, tries to talk a servant, Aggie, into staying on in the family service. At the same time, an Architect and Psychiatrist begin to discuss plans for remodeling the house so that it can be used both as a home and as an office. The Architect recalls his past in such a room and his unwilling participation in agonizing family-dinner rituals. To the hesitant Psychiatrist, he proposes that the dining room, a relic, be sacrificed for office and reception space.

A children’s birthday party for a boy named Brewster follows, hosted by Peggy, Brewster’s mother. Ted, the father of one of the children, arrives to pick him up, and as the party progresses, Ted and Peggy, sotto voce, discuss their deteriorating adulterous liaison. When the children go off to play party games, the Grandfather, an elderly man of about eighty, enters and sits at the head of the dining table. He is approached by Nick, his grandson, who is sent to ask him for financial support for his education at a private, exclusive preparatory school. After remarking wistfully that things were different when he was young and that times are not so easy, the Grandfather agrees to help. Toward the end of the Grandfather’s litany, Paul begins examining the table, checking to see why it developed a wobble, which worries its owner, Margery. After crawling under the table with Paul, Margery discovers, to her dismay, that the table, made in 1898, is an American replica of an earlier English piece. The two plan to repair the table together and leave for the kitchen to seal their partnership with a drink.

In the wake of their departure, celebrants gather in the dining room for a Thanksgiving dinner. Two of them, Stuart and Nancy, try to explain the situation to the Old Lady, Stuart’s mother, but she is completely disoriented and fails to understand what is happening. The men at the dinner sing for her, and for a moment it appears that she might come around, but when they finish, the Old Lady, lost in her youth, asks them to call for her carriage, noting that her mother expects her home for tea. Stuart and his brothers escort her out, leaving the women behind to commiserate about the situation over stiff drinks.

Two girls, Helen and Sarah, released from school, enter next and discuss raiding the pantry liquor supply. In the absence of Sarah’s mother, they plan to invite some boys for a party. Kate and Gordon, illicit lovers, appear, fresh from a guilty tryst. They attempt to regain their composure over tea but are taken aback by the unexpected arrival of Kate’s son, Chris, whose coldness toward Gordon reveals his suspicions about the relationship between Gordon and his mother. Aunt Harriet, an aristocratic host, lectures her nephew, Tony, a student at Amherst, on good manners and the proper use of the elegant table pieces she shows him. After taking notes and pictures, he explains that he is going to use the material in an anthropology class presentation on the WASP culture of the northeastern states. Irate over the disclosure, Aunt Harriet orders him to leave.

Jim and his mature, married daughter, Meg, file into the room. As Jim fortifies himself with Scotch, Meg subjects him to a recital of her problems, which involve the breakdown of her marriage and her affairs with a married man and another woman. She hopes to renew herself with a visit at home, but Jim will only agree to letting her stay for a brief, temporary visit.

Standish, defending family honor, explains to his wife and children why he has to go to his club to try to force an apology from Binky Byers, who while in the steam bath publicly alluded to the homosexuality of Standish’s brother, Uncle Henry. An old man, Harvey, then begins to explain to his son, Dick, that he wants him to comply with the funeral arrangements he made for himself. He confides that he has already written his own obituary and planned his funeral service, including very specific written directions. He also explains that he is leaving his best legacy, the dining room, to Dick.

At the end, Annie, the servant, explains to Ruth, her employer, that she is retiring and will no longer be available for service to the family. After Annie leaves, Ruth speaks wistfully of a recurrent dream she has, a dream of a perfect party, to which all her family and friends are invited. The Host then comes in, and, as the guests gather, raises a glass of wine and proposes a toast to everyone.