Two brothers compete for their father's approval and a woman's love.

In 1917, rancher Adam Trask has moved from his ranch to the town of Salinas, California with his twin sons, Caleb and Aron, whom he named after Biblical characters. Despite their fondness for each other, the boys are very different in temperament. While Aron is pious and a source of pride for Adam, the troubled Cal behaves erratically. Unable to understand Cal's restless spirit, Adam is often critical of the boy and fails to praise his hard work and inventiveness. Cal yearns for signs of Adam's love and respect, but his father's disapproval provokes him into playing rebellious pranks. Adam believes that his former wife Kate went east after abandoning the family, but has told his sons that their mother died shortly after their birth in order to spare them pain. Aron, therefore, believes his mother is "in heaven." However, Cal secretly discovers that she is alive and running a brothel in nearby Monterey, and is tormented to think that he is "bad" like her. Adam conceives of an ingenious idea to transport lettuce across the country in railroad cars, preserving the vegetables in ice. However, his experiment fails when the train is delayed by a snow slide and the ice melts, causing him to lose his fortune as well as the lettuce crop. It is Cal, not Aron, who fully senses Adam's disappointment. To help him, Cal takes advantage of wartime economics by going into business with family friend, Will Hamilton, growing and selling beans at a huge profit. To raise $5,000 to pay for seed, Cal approaches Kate and asks for the money. After chatting with him about the family and her business, the dissipated woman finds Cal "a likable kid" and writes him a check. The Salinas townspeople, naïvely believing they will win the war in a few weeks, celebrate the United States' decision to join the war against the Germans in Europe. During the town's parade, Aron, who is opposed to the war, watches morosely, while Cal plays pranks behind the crowd's back. Later, after hearing news of the thousands of casualties, including some of their own boys, the townspeople take out their frustration by throwing rocks at the shop window of long-respected, German-born storekeeper, Gustav Albrecht, who refuses to believe the propaganda about his former countrymen. Distressed by the hostility, Adam, who is on the draft board, considers retreating back to his ranch. When he expresses anxiety over money, Cal, keeping his bean venture secret, tells him not to worry. At a carnival, Cal abandons his date to rescue Aron's girl friend Abra from the unwanted attentions of a soldier. Abra, who is both frightened and fascinated by Cal's sometimes outlandish behavior, senses a bond because of the troubled relationship she has with her own father. While waiting for Aron, Cal and Abra take in the carnival sights together and board the Ferris wheel. There, the curious Abra asks Cal about his many girl friends and wonders if she is good enough for Aron, who projects an image of his idealized mother onto her. Sitting close together, they grow attracted and kiss, but she breaks it off, crying that she loves Aron. Down below, people in their wartime fervor are harassing Albrecht. Seeing Aron try to mediate the dispute, Cal climbs down the rigging of the Ferris wheel to help him. The crowd follows Albrecht home where a fight erupts, but order is restored when the sheriff, Sam, a close friend of Adam who has been sympathetic to Cal, calls the citizens by name and gently sends them to their homes. Afterward, when Abra appears wearing Cal's coat, Aron jealously accuses Cal of starting the fight and Cal, feeling hurt and betrayed, punches him several times. Later, Abra finds Cal at a saloon, ashamed of himself for hitting Aron so hard. She asks him to confirm that their kiss had no meaning, but Cal is preoccupied with thoughts about Adam's preference for Aron. For Adam's birthday, Cal plans a party, during which he plans to present his father with the money he made from selling beans. While Abra helps him decorate and cook the meal, Cal expresses his desire that his gift be better than Aron's. Adam is touched by Cal's efforts, but rejects the gift of wrapped money, refusing to profit from the war. Aron, surprises everyone, including Abra, by announcing that he and Abra are engaged, prompting Adam to slight Cal by saying that "this is the best present, the living of a good life." Broken, Cal cries out in anguish and leaves, followed by Abra, who tries to comfort him. Aron, accusing him of being "mean and vicious," orders him never to touch her again. Challenging Aron to face reality, Cal persuades his brother to accompany him to Monterey, where he takes him to the brothel and cruelly introduces him to Kate. Shocked to discover that his mother, whom he has idolized, is a hardened, drunken prostitute, Aron goes off alone. Cal returns home, planning to leave town with the money to start a business. When Adam asks about Aron, Cal says, "I'm not my brother's keeper." Accusing Adam of not loving him because he is a reminder of Kate, Cal admits he has been jealous of Aron all his life. After claiming he no longer wants Adam's love, he says to Abra that he does not want "any kind of love anymore," because it does not "pay off." Sam arrives, saying that Aron has gotten into drunken fights and has decided to enlist as a soldier. Adam, Cal and Abra go to the station, where Aron has boarded a troop train. However, they never talk to Aron, who, drunk and in shock inside the train, smashes his head through the glass window of the train, laughing as the shattered glass falls on Adam. When Aron's train departs, Adam collapses into Cal's arms. Back at the house, the doctor tells Cal that Adam has suffered a paralyzing stroke and might not survive the night, then leaves his patient in the care of a self-centered and insensitive nurse. Having lost faith in Cal, Sam recites lines from the Biblical story of Cain and Abel, and suggests that he leave town. After apologizing to his father, Cal begins packing. Alone with Adam, Abra confides in him that she loves Cal and asserts that he will never be a man without the love Adam has unintentionally withheld from him. She begs Adam to ask Cal for something, as a sign that he loves and needs him, before it is too late. Cal, at Abra's insistence, returns to his father's room and tells him that he has heeded his words, that "man has a choice and the choice is what makes the man." With all his strength, Adam asks Cal to fire the annoying nurse and then whispers, "You stay with me. You take care of me." After kissing Abra, Cal pulls up a chair next to Adam's bed.