The play opens on the Cabot family’s New England farm in 1850. The farmland is incredibly rocky, and oppressive Elm trees tower over the farmhouse, leaving it in constant shadow. Ephraim Cabot (who goes by just “Cabot”) owns the farm, and his three adult sons—Simeon, Peter, and Eben—all despise him. Simeon and Peter, who are Cabot’s sons from his first marriage, hate their father for subjecting them to hard lives of physical labor on the farm, and they dream of running away to California to strike it rich in the Gold Rush. But Eben, Cabot’s son from his second marriage to Maw, hates Cabot for subjecting Maw to such hard farm labor and literally working her to death. Maw died when Eben was a teenager, and ever since then he’s been consumed with the desire to avenge her death and claim back the farm, which he believes rightfully belongs to Maw, not Cabot.
On a visit to town, Eben learns that Cabot, who’s been out of town for a few months, has just remarried. Cabot’s sons are furious, as this threatens their right to inherit the farm. The next day, Eben hastily decides to buy Simeon’s and Peter’s shares of the farm—since Eben’s the youngest of the brothers, having Simeon and Peter out of the way will help him more easily claim the farm back from Cabot. Simeon and Peter carefully weigh their options and decide to accept, planning to use the money to fund their trip to California. When the ageing Cabot returns to the farm with his young wife Abbie Putnam, Simeon and Peter promptly leave to seek their fortunes, cursing Cabot as they go. Meanwhile, an excited Abbie explores her new home and meets Eben. Though the two are attracted to one another, Eben’s angry that she thinks the farm is hers.
Two months later, Abbie is sitting on the porch. She flirts with Eben (much to his frustration), who is on the way to see his sweetheart, Minnie. Feeling jealous, Abbie vengefully tells Cabot that Eben tried to seduce her, but when Cabot vows to kill Eben for this, Abbie regrets saying anything and tries to pass her comment off as a joke. Relieved, Cabot leans in to kiss Abbie, but she pulls away in disgust. Abbie convinces Cabot to leave the farm to her if she has a baby, and he agrees.
That night, Cabot and Abbie are in bed. Her eyes are locked on the wall to the adjoining bedroom, where Eben sits in his bed, similarly fixated on the wall that divides him from Abbie. Oblivious to this, Cabot rambles on to his wife about how he’s worked hard for years, relentlessly digging stones out of the farm’s rocky, unforgiving land, and how he believes God doesn’t like easy success. He’s also been lonely for years: his first wife and second wife (Maw) both died, and when Maw’s parents tried to steal the farm from him, this caused him even more trouble. Realizing that Abbie isn’t listening and feeling unsettled by her, Cabot leaves in a huff to sleep in the barn.
With Cabot out of the house, Abbie then goes into Eben’s room and attempts to seduce him. Tough the desire between them is palpable, Eben forces himself to resist. But when Abbie leaves Even’s room for Maw’s parlor (which has remained empty since Maw’s death), Eben follows her in a confused daze, calling out for Maw. The parlor feels creepy at first to both Eben and Abbie, but the room’s energy soon warms. Abbie suggests that this is a sign that Maw wants them to be together, and Eben runs into Abbie’s arms, half out of grief for Maw, half out of desire for Abbie. Abbie says that she’ll love him just like Maw did—that Eben will be like a son to her—and they kiss passionately and make love. The next morning, Eben is overjoyed that Maw can finally rest in her grave.
One year later, there’s a party at the farmhouse. Upstairs is a conflicted-looking Eben and a baby in a cradle. Downstairs, Cabot is partying drunkenly, while Abbie, who looks pale and weak, keeps asking where Eben is. The crowd gleefully mocks Cabot behind his back, clearly sensing that Eben, not Cabot, is the father of Abbie’s baby, though Cabot doesn’t know this. After Cabot heads to the barn to sleep off his drunkenness, Abbie joins Eben upstairs, and they look lovingly at the baby. Down below, the crowd celebrates the miserly Cabot being fooled.
Later that night, Eben runs into Cabot outside. Cabot mocks his son, saying that Eben will never have the farm with Abbie around—she even plotted to have a child just so that she could claim it for herself. Shocked and enraged, Eben springs up to confront Abbie, but Cabot pins Eben to the wall by his neck, mocking him further. A terrified Abbie rushes to Eben’s aid as Cabot releases him and walks away. Eben curses Abbie for manipulating him, and he blurts out that he wishes the baby were dead. Abbie is desperate to prove to Eben that her loyalties lie with him and not the baby or the farm, but Eben doesn’t believe her. He vows to leave for California in the morning.
Just before dawn, Abbie is standing over the baby’s cradle, when she suddenly lets out a cry and shrinks away in horror. She runs downstairs, flings her arms around Eben, and says that she’s killed “him” to prove her love to Eben. Eben assumes that Abbie killed Cabot, and he's thrilled. Laughing shrilly, Abbie admits that would have been smarter. She explains that she killed their baby to prove to Eben that she doesn’t want to steal the farm. Eben is horrified, and he immediately leaves to tell the Sheriff, leaving Abbie in tears, helplessly begging Eben to love her again.
Cabot wakes up to find Abbie looking pale and sick, and she admits that she killed the baby. Shocked and engaged, Cabot grabs Abbie, but she pushes him away furiously and spits that the baby is Eben’s. Cabot is shocked. Eben suddenly rushes back in, crying that he told the Sheriff about the murder but was instantly overcome with regret, because he really does love Abbie. They run into each other’s arms. Disgusted, Cabot says that both Abbie and Eben should be hanged.
Cabot quickly decides to abandon the farm and leave for California, but when he opens a floorboard to dig out his life savings, he’s shocked to find that his money is gone. Eben admits that he used it to pay Simeon and Peter in exchange for their portions of the farm. Suddenly realizing he’s going to be lonely again, Cabot murmurs that he would never have turned Abbie in like Eben did. He commits himself to continuing to slave away on the farm and dying alone, thinking it’s God’s will.
The Sheriff arrives to arrest Abbie for the murder, and Eben turns himself in as well, although Abbie begs him not to. As the Sheriff leads the pair away, they affirm their love for each other. The Sheriff looks around the farm, noting that it’s very pretty and that he wishes he owned it.