American adventurer Jim Bowie fights to make his way in the lumber business.

In 1825, Jim Bowie journeys to New Orleans from his family's backwoods home in Bayou Sara to sell some lumber. His brothers caution Jim, a carefree young man whose only interest is in throwing knives, to hold out for a good price. In New Orleans, Jim makes the acquaintance of French painter James Audubon, who has angered the wealthy de Bornay family by painting birds instead of completing his portrait of the beautiful Judalon de Bornay. For verbally defending Audubon, Jim is challenged to a duel by Judalon's brother Narcisse. The challenge surprises Jim, who never intended to insult Narcisse, but Audubon explains that the upper classes of Louisiana's French-dominated society are strictly governed by "the code" of honor. Jim's use of gentle humor to prevent the duel charms Narcisse, and the two become friends. Narcisse worries, therefore, when Jim falls in love with Judalon, who is proud and spoiled. Judalon allows Jim to kiss her at a ball, but his passionate marriage proposal makes her angry, as Judalon has no intention of living on a bayou. Assuming that Jim has insulted Judalon, another suitor named Henri Contrecourt challenges him to a duel. Narcisse intervenes and is killed in the ensuing confrontation with Contrecourt. Jim then agrees to face Contrecourt, an excellent swordsman, armed only with his knife, and the two fight in a darkened chamber. To the surprise of the assembled crowd, Jim kills Contrecourt. He then sells the lumber mill and returns home with a plan to get rich by planting cotton in the bayou country. Over the next few years, the Bowies do become wealthy, but their business rivals, headed by Natchez cotton grower Juan Moreno, try to ruin them. Undeterred, Jim buys an unknown racehorse that defeats Moreno's steed in a race. Most of Moreno's cohorts pay Jim the money they bet, but Jim expects trouble and asks an expert blacksmith named Black to make him a strong knife. Black shapes a piece of a meteor into the knife, thereby making it unusually durable and sharp. Later, Jim discovers that Judalon has wed a New Orleans gentleman named Philippe de Cabanal, but after kissing Jim, she tells him that she is planning a divorce. Jim's brother suspects that she now wants to marry Moreno, but Jim is devoted to Judalon and refuses to listen. Following a duel, Moreno and his colleagues begin shooting at Jim and his friends, and after Moreno injures him, Jim stabs him to death. Judalon, unhappy because Moreno had promised to secure a bill of divorcement for her, promises to accompany Jim to a new home in Texas if he first has her husband released from a gambling debt owed to "Bloody Jack" Sturdevant. Jim defeats Sturdevant in a knife fight, but Judalon sends word that she has decided to remain with Philippe. En route to Texas, Jim is nearly killed by Sturdevant's men. He is found and nursed to recovery by Ursula de Veramendi, the Spanish daughter of the Texas vice governor. Jim soon proposes to Ursula, but she suspects he still loves Judalon. Jim returns to Louisiana to sell his lands, and on a steamboat, he encounters Judalon and Philippe. Jim learns that Philippe has lost all his money in a card game, but he exposes the gamblers as cheats and returns Philippe's money. After Judalon threatens to leave Philippe for her old admirer, the angry husband sneaks into Jim's room with a gun. At the same time, Sturdevant, seeking revenge for his earlier injury, hides in Jim's cabin, intending to kill him, but instead stabs Philippe by accident. Philippe shoots Sturdevant before dying himself, and Judalon's obvious glee at her husband's death stuns Jim. He leaves her, then drops his knife into the river and returns to San Antonio to marry Ursula.