It is the late 1870s. Captain Woodrow F. Call and Captain Augustus “Gus” McCrae, two famous retired Texas Rangers, run the Hat Creek Cattle Company and Livery Emporium in the small Texas border town of Lonesome Dove. Working with them are Joshua Deets, an excellent black tracker and scout from their Ranger days; Pea Eye Parker, another former Ranger who is reliable but unintelligent; Bolivar, a retired Mexican bandit who works as their cook; and Newt Dobbs, a 17-year-old boy whose mother was a prostitute named Maggie and whose father is widely thought by the outfit to be Call, though Call has never acknowledged this.
Jake Spoon, another former Ranger, arrives in Lonesome Dove after an absence of more than 10 years, during which he has travelled widely across the United States. He is on the run, having accidentally shot a dentist in Fort Smith, Arkansas. The dentist’s brother happens to be the sheriff, July Johnson.
Reunited with Gus and Call, Jake’s description of Montana inspires Call to gather a herd of cattle and drive them north to begin the first cattle ranch north of the Yellowstone River. Call, who has grown listless in retirement, is attracted to the romantic notion of settling pristine country. Gus is less enthusiastic but changes his mind when reminded that the love of his life, Clara, lives on the Platte River near Ogallala, Nebraska, which would be on the route to Montana. The Hat Creek outfit rustles cattle from across the border in Mexico and recruits local cowboys in preparation for the drive.
Ironically, Jake Spoon decides not to go at all, having made himself comfortable with the town’s only prostitute, Lorena Wood, who is smitten with him after he promises to take her to San Francisco. At Lorena’s insistence, however, she and Jake ultimately trail along behind the cattle drive.