In the film’s opening scene, we are introduced to brothers Gilbert and Arnie as they wait for the arrival of the annual summer Airstream convention that passes through their small town of Endora, Iowa. It is Gilbert’s responsibility to care for Arnie, his developmentally-delayed brother. Later, we are introduced to the remainder of the Grape family. Amy, the oldest sister, does all of the cleaning and cooking for the household. Ellen, the youngest sister, chooses to focus on her appearance as a means of distracting her from her dysfunctional family life. Bonnie, their mother, is depressed and morbidly obese. We learn that Bonnie has not left the house since her husband died by committing suicide in the family’s basement seven years ago. Arnie is about to celebrate his eighteenth birthday, a feat considering that he was not expected to see this age due to his illness. The entire family is busily planning for his birthday party in order to celebrate.
Although Gilbert says that “nothing happens” in his small Iowa town, we learn that Gilbert’s life at home is filled with daily obstacles. Gilbert’s affair with Betty, a married mother of two, brings him more trouble than pleasure. Additionally, Gilbert is constantly having to run after Arnie, who enjoys scaling his town’s water tower at any chance he can get. Although Gilbert is friends with Tucker and Bobby, we learn that his mounting responsibilities often lead him to feel isolated and unsupported.
Next we are introduced to Becky and her grandmother, who are traveling through Endora for the annual caravan parade. However, when their RV breaks down, the two are forced to spend the week in the small town. While in Endora, Becky gets to know Gilbert and Arnie. Gilbert becomes romantically interested in Becky, as she represents a world beyond his current claustrophobic life. As Gilbert starts spending more time with Becky, Betty grows increasingly jealous.
Gilbert’s house, the only material remnant of his father’s legacy, is collapsing under the weight of his obese mother. Additionally, as Gilbert starts becoming closer to Becky, he turns away from his familial responsibilities. The climactic point of the story occurs when Gilbert, eager to return to his date with Becky, leaves Arnie in the bathtub to wash himself. When Gilbert returns home the following morning, he finds Arnie still sitting in the bathtub. This incites Arnie’s fear of bathing, which intensifies further throughout the film.
Meanwhile, Betty, jealous of Gilbert’s new romantic prospect, seeks to seduce and trap her young lover. She facilitates a meeting between Gilbert and her husband, which solely manifests in Mr. Carver’s discussion of the Grape’s absent insurance policy. In the middle of their meeting, Mr. Carver receives a frantic call from Betty and demands that the two return to her house at once. Upon arrival, they see that their kitchen is smoking and that Betty is frantic. Later that night, Mr. Carver is found dead in his children’s swimming pool. Though the entire town claims that Betty murdered her husband, Bobby, the coroner, insists that it was due to a heart attack. Mrs. Carver leaves town due to the scandal.
On another date with Becky, Gilbert finds that Arnie has, once again, gone missing. They find that he has scaled the water tower, and he has been taken into custody by the town authorities. After Bonnie finds out that her son is in jail, she decides to leave her home for the first time in seven years. Upon her arrival at the police station, Bonnie is gawked at and ridiculed for her obesity. Although she successfully emancipates Arnie, Bonnie feels an unparalleled sense of shame and self-hatred. Meanwhile, Gilbert is forced to shop at the rival grocer, FoodLand, in order to purchase Arnie a birthday cake. After becoming aggravated with Arnie’s behavior, Gilbert slaps his younger brother. After Arnie runs away to Becky’s campsite, Gilbert is forced to admit his fault and reconcile with both his brother and Becky.
At Arnie’s birthday party the next morning, Bonnie refuses to leave her home. She calls Gilbert inside at first to chastise him, though after some time she admits her vulnerability and praises her son for taking care of her family. Later, Gilbert introduces Becky to Bonnie. Though they are initially awkward with one another, Bonnie seems to be put at ease by Becky’s presence.
That night, Bonnie decides to ascend the stairs to her room for the first time in seven years. Later in the night, she passes away in her sleep. The Grape children, stumped at how to give Bonnie a funeral that won’t make her a town spectacle, ultimately decide to burn their home with Bonnie inside. The film jumps to one year later, and it appears that all of the children have since moved on with their lives. Amy takes a job at a bakery in Des Moines, and Ellen is anticipating switching schools. The film ends on a moment paralleling the beginning, Gilbert and Arnie remain in a similar position as the first scene, awaiting the arrival of the summer caravans. But this time, they are also excited for the return of Becky and the prospect of starting their lives anew.
