After suffering a great personal loss, 25-year-old Theodore Roosevelt abandons New York politics for the lawless Dakota Badlands, where he plans to become a cattle rancher at the height of the Beef Bonanza. The former politician must now navigate a dangerous path through the Badlands, where his youth and physical frailty make him an easy target. Upon arriving in the frontier town of Medora, he immediately squares off with a gunslinging bully. Time and again, Roosevelt must prove his strength on the forty-mile journey to secure the property for his cattle ranch. Along the way, he is haunted by memories of loss, and he survives a first encounter with a powerful and deadly landowner, the Marquis de Morés. With the help of his lumberjack mentor, Bill Sewall, and his cowboy partner, William Merrifield, Roosevelt establishes the sprawling Elkhorn Ranch. The adventures and hardships of building Elkhorn will transform the young Roosevelt into a true cowboy and set him on a path to greatness.

Theodore Roosevelt must fend off a powerful neighbor, the Marquis de Morés, who is intent on seizing Roosevelt’s newly built Elkhorn Ranch in an underhanded land grab. To save his ranch, Roosevelt travels to the home of the Marquis and his beguiling wife, Medora, who is just as cunning as her husband. Back at Elkhorn, Roosevelt’s new ranch hands, former lumberjacks Bill Sewall and Wilmot Dow, are attempting to master the saddle when their bronc-busting lessons are suddenly cut short by the arrival of the Marquis’ henchmen. For one long night, Elkhorn’s very survival hangs precariously in the balance.

Roosevelt’s efforts to prove himself a capable cowboy are off to a shaky start when he’s mocked by a loudmouthed ranch hand. On the spot, Roosevelt challenges the new hire to put up his fists or shut up. After Roosevelt proves his mettle, the two become fast friends. But soon, Roosevelt’s reputation takes another hit when a neighboring rancher accuses his men of rustling cattle. To save Elkhorn’s good name, Roosevelt and his men must capture the real thief and return the stolen livestock. In town, Medora buys a rundown inn and transforms it into the Hotel de Morés. Her first act is hiring a new manager, an impressive young woman named Rosie Maddox. When Medora realizes that a cattle rustler might be staying in the hotel, she tasks Rosie with uncovering the evidence.

When the Elkhorn Ranch is invaded by a gang of horse thieves, Theodore Roosevelt and his men put up a valiant fight, but the thieves escape with a string of new horses. An indignant Roosevelt joins up with the Stranglers, a posse of vigilantes led by Granville Stuart who mete out their own brand of frontier justice in the absence of any law enforcement in the Badlands. When they catch up with one of the thieves, Roosevelt learns firsthand that frontier justice isn’t always just. Meanwhile, the business of Elkhorn is thrown into chaos when Merrifield meets with a Chicago beef merchant behind Sewall’s back. Sewall takes matters into his own hands by striking a deal with Medora, an act of defiance that has disastrous consequences. When Wilmot Dow meets the lovely Rosie at the Hotel de Morés, the two youngsters spark an immediate connection.

Now that his cattle operation is up and running at Elkhorn Ranch, Theodore Roosevelt agrees to be photographed by a newspaperman. Determined to look the part, Roosevelt seeks out a seamstress to commission an authentic buckskin suit. While the cantankerous seamstress warns Roosevelt that buckskin isn’t well suited for the Badlands, Roosevelt collapses suddenly with another bout of enteritis, an illness that has plagued him his entire life. Out here on the frontier, without access to the proper medication, it suddenly becomes a matter of life or death. In a race against the clock, his trusted ranch manager, Bill Sewall, rides desperately into the Badlands to find the Sioux village that may have a remedy to save his friend. Meanwhile, the Marquis and Medora find themselves on the brink of financial ruin. To save their business empire, they decide to call in their debts at gunpoint.