A young boy becomes mute after seeing his mother killed in the Civil War and his father decides to take him and their dog on a trek to find a cure for his condition, but the road ahead is full of evil sheepherders and hard-to-find money.

After the Civil War, former Confederate soldier John Chandler brings his ten-year-old son David to Aberdeen, Illinois in search of a doctor. In the office of kindly Doc Enos Davis, John reveals that David, who is otherwise completely healthy, lost his voice after witnessing his mother being killed in a fire. Enos informs John that, although the malady is likely psychological, a Dr. Eli Strauss in Minnesota might be able to help. Newly hopeful, John brings David to the local store to buy supplies for their trip, but their way is blocked by the sheep herd of rancher Harry Burleigh and his sons, Jeb and Tom. John instructs their dog, Lance, to clear the street of the sheep, and the expert herding dog complies, attracting the attention of the Burleighs. As John trades silver for supplies inside the store, they hear Lance bark and rush out, to discover that the Burleigh brothers are attempting to steal the dog. John is forced to fight them, and is winning when Harry joins the fray and knocks him out. David, distraught, throws himself in front of a passing wagon to ask the driver, Linnett Moore, for help. Moved by the medallion David wears identifying him as a mute, Linnett holds him as Harry pours bourbon over John's head and then tells the approaching sheriff that John drunkenly attacked him. In court, Judge Morley, who dislikes Southerners, sentences John to thirty days in jail or $30, and when John cannot pay, Linnett announces that he can work the fine off on her farm. Once there, Linnett gruffly informs John about the amount of work he will be required to perform, but simultaneously tidies up the bunkhouse to make it comfortable. When she asks David for help with the horses, John announces that David is not to work, but later both are proud to see David disobeying his father's orders. Weeks pass, with both father and son enjoying their hard work and its effect on the farm, as well as Linnett's attentions. Despite John's contentment, he warns Linnett that he will be taking David to Minnesota as soon as his debt is repaid. One day, the Burleighs drive their sheep directly onto Linnett's land. Linnett prepares to shoot at them, but John stops her, instead using Lance to control the herd. While local dog breeder Birm Bates watches, impressed, the Burleighs are forced to retreat. Birm immediately offers to buy Lance, but John states that the dog is not for sale, and as Linnett observes David's attachment to Lance, she deduces John's motives in keeping the dog. That night, after Linnett reads to David and speaks sign language with him, John thanks her, but cautions her that David should not grow too attached to her. He also reveals that David lost his mother when Yankee soldiers burned down their house, and then was sent to an orphanage, forcing John to search for the boy for months. Since then, they have been traveling from doctor to doctor, hoping to find a cure. Linnett begins to fall in love with father and son, but one day, Enos visits to announce that Dr. Strauss has agreed to see David free of charge. They must reach Minnesota within a week, however, and the trip will cost $300. Too proud to borrow money from Enos or Linnett, John tries to sell his horse, to no avail. Later, Harry offers John $500 to join him in convincing Linnett to give up her ranch, thus affording him free access to her grazing land, but John refuses. With no other options, he admits to Linnett that he plans to sell Lance to Birm, explaining that David's voice is more important than the dog, but Linnett strongly objects. As they argue, the Burleigh brothers set fire to the barn, and although David is terrified by the flames, he cannot yell a warning. Linnett and John finally see the fire and struggle to contain it, but fail. In the morning, Linnett confesses to John that now, with no place to store her crop, she must sell out, but John announces that he will stay to rebuild the barn and find another way to earn the money for his trip. That Sunday, John and David prepare to go to church, and are stunned to see the typically plain Linnett looking lovely in her Sunday-best clothes. In town, John overhears a nosy neighbor woman insinuating to Linnett that her living arrangement with John is fodder for gossip, and distracts Linnett by taking a photograph with her. They are interrupted by the sound of local boys calling David "dummy." Dismayed, John finds Birm and offers him Lance for $300, then convinces Linnett to take David to Minnesota while he watches the farm. As Linnett and David are leaving, John, unable to admit to the boy that he has sold Lance, tries to tell Linnett how he feels about her, but the wagon takes off too soon. Over the next days, Linnett sends John letters detailing David's progress and warning that he misses Lance terribly. John rebuilds the farm as he waits, optimistic that Dr. Strauss's planned operation will cure David. When they return, however, David remains mute, and is devastated to find Lance gone. John tries to explain but the boy hits his father and collapses in tears. Hoping to buy Lance back, John visits Birm, who reveals that the dog would not work for him, so he sold Lance to the Burleighs. After John then sees the ranchers dragging a howling Lance by a rope, he returns to the farm and straps on a gun, despite Linnett's pleas that Harry is deliberately antagonizing him in hopes of getting rid of him. Although she reveals that she cares only about him and David and will happily lose the farm to save them, John insists he must confront the rancher. John goes to Harry, who, after calling David "a dummy," grandly informs John he can have Lance back. As John retrieves the dog from the shed, however, Harry instructs his sons to shoot John as a dog thief. Meanwhile, David has followed his father, and appears just in time to see Jeb training his gun on the barn door. Desperate, David struggles until he is able to shout a warning, saving his father, who runs out to protect him. After John shoots Jeb, Harry advances on him in a murderous rage, and John is forced to shoot him. Although Tom raises his gun, he cannot bring himself to shoot the Chandlers. John takes David and Lance and returns to Linnett, who collapses in joyful tears when she hears David call her name.