In his haste to leave New Orleans and the threat of imprisonment, Flashman agrees to shepherd Susie Willinck and her company of prostitutes to Sacramento, where she intends to set up shop and make a bundle from gold miners. As wagon captain, Flashman is nominally in charge of his and Susie's (now his wife) collection of women, supplies, sex toys and the other forty-niners and invalids looking for a better life but he depends on the guidance of Richens Lacey Wootton to see them through. Unfortunately, Wootton becomes stricken with cholera. Flashman is left to get everyone to Bent's Fort in safety, which Comanches make difficult for him. Eventually, they reach Santa Fe, New Mexico, where Flashman absconds with two thousand dollars made from selling one of the prostitutes, Cleonie, to Navajos.
For safety in the wilderness, Flashman falls in with a group of travellers but he discovers them to be scalp-hunters, when they attack a band of Apaches. Flashman joins in but refuses to take any scalps or rape captive women, which saves him when the scalp-hunters are killed by the rest of the tribe on their return. He ends up marrying Sonsee-Array, the daughter of chief Mangas Coloradas, and becoming friends with Geronimo. He eventually escapes and is saved by Kit Carson on the Jornada del Muerto.
In 1875 Flashman returns to America with his wife, Elspeth. He meets George Armstrong Custer (whom Flashman had met during the US Civil War) and businesswoman Mrs. Arthur B. Candy, and later travels to Bismarck, North Dakota, to meet with Mrs. Candy and pursue a carnal relationship. However Mrs Candy is revealed to be Cleonie, the former slave girl, who is intent on revenge and at her connivance, he is kidnapped by Sioux and kept captive at Greasy Grass. He escapes just in time to see the defeat and death of Custer—possibly being the one who kills Custer—and to be partly scalped himself by his own illegitimate son from Cleonie, Frank Grouard, who by choice has been living as an Indian. The book ends with Flashman and his son travelling to Deadwood where Flashman meets another former acquaintance, Wild Bill Hickok prior to returning home.