A labor negotiator who serves as the narrator of this story is working in sleepy, slow-paced Starkfield, Massachusetts, a small town that seems to be perpetually buried under two feet of snow. An intelligent, educated man who is interested in science and engineering, he is also fascinated by one of the town’s citizens, Ethan Frome, a silent, introspective man whose once-powerful frame seems to have been worn down over time by the bitter cold and utter loneliness of living through countless Starkfield winters. After asking some of the townspeople about Ethan, he discovers that Ethan’s parents had died and left him a dilapidated farm, which he has struggled to maintain after surviving a near-fatal sledding accident over twenty years before. Ethan offers to take the narrator to work every day on his sled, and although he finds it hard to break down Ethan’s guard, he slowly finds out more and more about him. They both share an interest in science and engineering, and Ethan even shows him his decrepit farm. One day, a particularly bad snowstorm hits Starkfield, and Ethan offers the narrator a night in his home. As they enter the home, they both hear a querulous, whiny voice coming from inside the kitchen.
The story flashes back to over twenty years before the narrator meets Ethan. Ethan is 28 years old and has come to the town hall to pick up his wife’s cousin from a dance. Ethan’s wife, Zeena, is a hypochondriac who had taken care of his parents when they had been ill. When they had died, Zeena, who had once been a healthy, efficient, and skilled caregiver, became ill herself, and Ethan then had to take care of the farm and of his sickly, complaining wife. Ethan’s life of misery dramatically changes when Mattie Silver, Zeena’s second cousin, comes to live with them and to take care of her. Mattie, an orphan whose father had wronged his family members, has no place else to go, and even though she eagerly wants to help Zeena, she cannot because she has little knowledge of household management skills.
Ethan falls in love with Mattie and feels inspired and charged by her vitality, curiosity, and enthusiasm. In contrast to the cynical, caustic Zeena, Mattie is fascinated by everything in the world and rejuvenates Ethan, whose own spirit and energy had been eroded by the bareness of a long life in Starkfield. Ethan, however, keeps his feelings hidden because he is afraid of both Zeena and of the town’s reaction, and he does not even know if Mattie returns those feelings for him. As he watches her dancing inside the town hall with Denis Eady, the young man whom many speculate will soon propose to her, jealousy erupts inside him. He remains hidden while Mattie leaves the dance and watches in delight as she refuses a ride home from Denis Eady in his father’s cutter. When he surprises Mattie by suddenly falling into step with her, he is secretly pleased and excited by her gratitude and happiness. During their slow, intimate walk home together through a clear, cold Starkfield night, the two grow closer together, and Ethan falls even more deeply in love with her spunk and her wit.
One day, Zeena decides to travel to another town in order to see a doctor, and Ethan and Mattie are left alone for the night. Mattie has fixed a special dinner for the two of them and has put a scarlet ribbon, the color associated with her, in her hair. With a few moments of awkwardness and tension brought about by reminders of Zeena’s presence, Ethan and Mattie enjoy an intimate, comfortable evening together that creates an even more dramatic contrast in Ethan’s eyes between Mattie and Zeena.
During their dinner, the cat accidentally breaks a red pickle-dish that Zeena had treasured and hidden. Mattie is distraught because she had taken the dish out of hiding in order to make their dinner more special, but Ethan reassures her that he will be able to fix it with glue the next day and puts the plate back on its secret shelf, putting the broken shards together so that no one would be able to tell from a distance that it is broken. Their night together ends, and as Ethan goes to bed, he realizes that he is extremely happy even though he had not even touched her hand.
The next day, Ethan tries to find glue to repair the dish before Zeena returns, but it takes him too long to find the glue. By the time that he gets back to the farm, Zeena has already come home and announces to him that the doctor had ordered her to employ a hired girl so that Zeena would not have to lift a finger around the house. When Ethan protests, telling her that they couldn’t possibly afford to hire someone, she tells him that since Mattie will be leaving the house, there will be one less mouth to feed. Ethan, who is furious that Zeena would send Mattie away, remains silent because he has never been able to stand up to Zeena. He goes downstairs and passionately tells Mattie that he will not let her go, and Mattie bursts into tears, realizing that Zeena means to send her away.
At supper that night, Zeena decides to go to her secret hiding place in order to find an old medicine of hers, and she discovers that her pickle-dish has been broken. Mattie confesses to breaking the dish the night before, and Zeena explodes and tells her that she knew that she should have never taken her in and that people had advised her not to. Ethan, upset by this exchange between the two, retreats to his private parlor and tries to devise a plan so that he and Mattie could stay together. He concocts a wild idea to elope with Mattie to the West and leave Zeena with the farm, and he even begins to write a "Dear John" letter to Zeena, telling her that he is sorry that he and Mattie have gone away together. But he then realizes that they could never even find enough money to go to the West and that Zeena could certainly not take care of the farm by herself. Completely hopeless, he realizes that there is no way out of the situation and that he must go along with what Zeena has commanded.
The next day, Ethan rebels against Zeena’s desires and announces that he, and not his hired man, Jotham Powell, will take Mattie to the train station. On the way to the station, Ethan wants to tell her how he feels but is too unsure of her feelings for him that he checks himself from confessing. They drive past Shadow Pond, where there had once been a church picnic that Mattie had invited Ethan to, but he had refused to come. In the end, though, Ethan came to the picnic and surprised her, and as they travel slowly and sadly to the train station, they recall that picnic. Mattie, overcome with emotion, reveals the letter that he had begun to write to Zeena and asks him what he had intended to do. They confess their love for each other, and Ethan impulsively decides to take her on the sled ride that he had always promised to take her on. They safely make it through a first run, and Mattie suddenly proposes that they make another sled run - with the exception that this time, they purposely hit the big elm at the bottom of the slope so that they will not have to leave each other and will spend the rest of eternity together. They do, indeed, hit the elm, but they both survive.
The story flashes ahead to the decrepit, shabby Frome kitchen, where the middle-aged Ethan and the narrator are standing. In the story’s big surprise ending, it turns out that the whiny, querulous woman who had been speaking when they had come in is Mattie Silver, who had been left handicapped by the accident, and the tall woman who is tending to her is Zeena. Ethan introduces the two to the narrator, who realizes the utter misery and loneliness that must oppress the three of them, who will be sitting together in a cold, dark kitchen for the rest of their lives. Ethan even seems embarrassed about his threadbare kitchen, and gives an apologetic look to the narrator, who begins to piece together the details of Ethan’s tragic life.
The narrator returns to his temporary home the next day and tells Mrs. Hale, with whom he is lodging, and he tells her about his overnight stay at the Frome farm. Mrs. Hale reveals her own account of the smash-up and tells him that she and Mattie had actually been close friends before the accident and that immediately after it happened, Zeena became healthy again and had taken care of both Ethan and Mattie. She reveals to the fascinated narrator that after the accident, Ethan had recuperated over time and had struggled and persevered for years to keep the farm afloat so that the three of them could survive. She pities all three of them but feels the most badly for Ethan because of all the suffering that he has undergone. She even speculates that it might have been better for them if they had not survived the accident because of the endless misery that they now had to endure, waiting expectantly for death to pull one of them out of that cold, lonely kitchen.