Silas Marner is the weaver in the English countryside village of Raveloe in the early nineteenth century. Like many weavers of his time, he is an outsider—the object of suspicion because of his special skills and the fact that he has come to Raveloe from elsewhere. The villagers see Silas as especially odd because of the curious cataleptic fits he occasionally suffers. Silas has ended up in Raveloe because the members of his religious sect in Lantern Yard, an insular neighborhood in a larger town, falsely accused him of theft and excommunicated him.
Much shaken after the accusation, Silas finds nothing familiar in Raveloe to reawaken his faith and falls into a numbing routine of solitary work. His one attempt at neighborliness backfires: when an herbal remedy he suggests for a neighbor’s illness works, he is rumored to be a sort of witch doctor. With little else to live for, Silas becomes infatuated with the money he earns for his work and hoards it, living off as little as possible. Every night he pulls his gold out from its hiding place beneath his floorboards to count it. He carries on in this way for fifteen years.
Squire Cass is the wealthiest man in Raveloe, and his two eldest sons are Godfrey and Dunstan, or Dunsey. Dunsey is greedy and cruel, and enjoys tormenting Godfrey, the eldest son. Godfrey is good-natured but weak-willed, and, though secretly married to the opium addict Molly Farren, he is in love with Nancy Lammeter. Dunsey talked Godfrey into the marriage and repeatedly blackmails him with threats to reveal the marriage to their father. Godfrey gives Dunsey 100 pounds of the rent money paid to him by one of their father’s tenants. Godfrey then finds himself in a bind when Dunsey insists that Godfrey repay the sum himself. Dunsey once again threatens to reveal Godfrey’s marriage but, after some arguing, offers to sell Godfrey’s prize horse, Wildfire, to repay the loan.
The next day, Dunsey meets with some friends who are hunting and negotiates the sale of the horse. Dunsey decides to participate in the hunt before finalizing the sale, and, in doing so, he has a riding accident that kills the horse. Knowing the rumors of Silas’s hoard, Dunsey makes plans to intimidate the weaver into lending him money. His walk home takes him by Silas’s cottage, and, finding the cottage empty, Dunsey steals the money instead.
Silas returns from an errand to find his money gone. Overwhelmed by the loss, he runs to the local tavern for help and announces the theft to a sympathetic audience of tavern regulars. The theft becomes the talk of the village, and a theory arises that the thief might have been a peddler who came through the village some time before. Godfrey, meanwhile, is distracted by thoughts of Dunsey, who has not returned home. After hearing that Wildfire has been found dead, Godfrey decides to tell his father about the money, though not about his marriage. The Squire flies into a rage at the news, but does not do anything drastic to punish Godfrey.
Silas is utterly disconsolate at the loss of his gold and numbly continues his weaving. Some of the townspeople stop by to offer their condolences and advice. Among these visitors, Dolly Winthrop stands out. Like many of the others, she encourages Silas to go to church—something he has not done since he was banished from Lantern Yard—but she is also gentler and more genuinely sympathetic.
Nancy Lammeter arrives at Squire Cass’s famed New Year’s dance resolved to reject Godfrey’s advances because of his unsound character. However, Godfrey is more direct and insistent than he has been in a long time, and Nancy finds herself exhilarated by the evening in spite of her resolution. Meanwhile, Molly, Godfrey’s secret wife, is making her way to the Casses’ house to reveal the secret marriage. She has their daughter, a toddler, in her arms. Tiring after her long walk, Molly takes a draft of opium and passes out by the road. Seeing Silas’s cottage and drawn by the light of the fire, Molly’s little girl wanders through the open door and falls asleep at Silas’s hearth.
Silas is having one of his fits at the time and does not notice the little girl enter his cottage. When he comes to, he sees her already asleep on his hearth, and is as stunned by her appearance as he was by the disappearance of his money. A while later, Silas traces the girl’s footsteps outside and finds Molly’s body lying in the snow. Silas goes to the Squire’s house to find the doctor, and causes a stir at the dance when he arrives with the baby girl in his arms. Godfrey, recognizing his daughter, accompanies the doctor to Silas’s cottage. When the doctor declares that Molly is dead, Godfrey realizes that his secret is safe. He does not claim his daughter, and Silas adopts her.
Silas grows increasingly attached to the child and names her Eppie, after his mother and sister. With Dolly Winthrop’s help, Silas raises the child lovingly. Eppie begins to serve as a bridge between Silas and the rest of the villagers, who offer him help and advice and have come to think of him as an exemplary person because of what he has done. Eppie also brings Silas out of the benumbed state he fell into after the loss of his gold. In his newfound happiness, Silas begins to explore the memories of his past that he has long repressed.
The novel jumps ahead sixteen years. Godfrey has married Nancy and Squire Cass has died. Godfrey has inherited his father’s house, but he and Nancy have no children. Their one daughter died at birth, and Nancy has refused to adopt. Eppie has grown into a pretty and spirited young woman, and Silas a contented father. The stone-pit behind Silas’s cottage is drained to water neighboring fields, and Dunsey’s skeleton is found at the bottom, along with Silas’s gold. The discovery frightens Godfrey, who becomes convinced that his own secrets are destined to be uncovered as well. He confesses the truth to Nancy about his marriage to Molly and fathering of Eppie. Nancy is not angry but regretful, saying that they could have adopted Eppie legitimately if Godfrey had told her earlier.
That evening, Godfrey and Nancy decide to visit Silas’s cottage to confess the truth of Eppie’s lineage and claim her as their daughter. However, after hearing Godfrey and Nancy’s story, Eppie tells them she would rather stay with Silas than live with her biological father. Godfrey and Nancy leave, resigning themselves to helping Eppie from afar. The next day Silas decides to visit Lantern Yard to see if he was ever cleared of the theft of which he was accused years before. The town has changed almost beyond recognition, though, and Silas’s old chapel has been torn down to make way for a new factory. Silas realizes that his questions will never be answered, but he is content with the sense of faith he has regained through his life with Eppie. That summer Eppie is married to Aaron Winthrop, Dolly’s son. Aaron comes to live in Silas’s cottage, which has been expanded and refurbished at Godfrey’s expense.