Based on Bret Harte's story, a gaming-hall owner adopts a lucky orphan and prospers until a minister, school-teacher, and a citizens committee arrive.
In California in 1850 Golden Nugget owner John Oakhurst (Preston Foster) fires a dealer for cheating and helps deliver a baby girl; but her mother died. John keeps the baby for luck, and eight years later his business has grown. His partner, the Duchess (Margaret Irving), wants Luck (Virginia Weidler) to go to school. Minister Sam Woods (Van Heflin) and school-teacher Helen Colby (Jean Muir) arrive, and John offers his gaming-hall for a church service. Sam preaches, but Sonoma (Bradley Page) comes in and laughs. John bets Sonoma and raises money for a church. When John makes Luck go to bed, Sonoma objects; but John pulls a gun, and they drink together.
John makes Luck go to school, and Luck says that Helen has her hooks in him. Two weeks later John's business has suffered, but he gives Helen money for the school. The drunk Indian Jim (Monte Blue) shoots at the bar, and bartender Kentuck (Si Jenks) kills him. Citizens complain, and Sam is delegated to talk with John. Luck prays, and Helen puts her to bed; but Luck escapes. Sam finds John with Sonoma. John tells Sam that he opposes vigilantes. Luck plays cards, and Helen comes in for her. Sam gives Luck to Helen, and Sonoma slaps both Sam's cheeks. Then Sam knocks Sonoma down. Jim runs in front of Helen and is shot by Sonoma. John criticizes Helen and collapses. Sam proposes to Helen that they leave with Luck, who says that John loves Helen. A doctor suggests that John needs prayer, and Sam pleads for him. Helen kisses John, and he recovers.
John and Helen see a new sign about law put up by the citizens committee. John is sent a yellow ribbon from Sonoma; but John says law is good. The Duchess tells John that he sold out; but Helen commends him. Then John goes to meet Sonoma, and the Duchess tells Helen to get the vigilantes. Sonoma shoots and misses; but John shoots Sonoma, who then shoots his friend for shooting at John. The vigilantes find two men dead; but instead of a rope, Sam suggests that John be driven out. In town Luck asks John to take her with him; but John leaves with the Duchess, Kentuck, and Uncle Billy (Al St. John), while others go with Charlie (Billy Gilbert). Helen joins John, and the ladies sleep in an empty shack. Uncle Billy takes their provisions and horses. As it snows, John sends Kentuck to Poker Flat. John tells Helen to keep awake; but she passes out. Kentuck and the rescue party find the Duchess dead and revive Helen. Luck and Sam find John dead with a suicide note.
Helen believes that she can build empire by pushing her man in the right direction; but in the violence of the wild west that fails in this case.