In December of 1875, George A. Custer hires a detective to solve the killing of a popular Seventh Cavalry officer. Lysander Hughes is a former Texas Ranger and San Francisco policeman. He's also wanted for the murders of four men -- Yankees who killed his fiancee. Lysander goes undercover as an enlisted man, and he encounters a female journalist who is also pursuing the case. Verity Winslow is a woman in a man's profession, and she's got a chip on her shoulder the size of the Black Hills because of it. Driven to make a name for herself, Verity has a mysterious informant who claims to know who killed the officer. Lysander and Verity mix as well as oil and water, but they are forced to work together to solve the case. They learn that the murdered officer was not as popular as he was purported to be, and that more than one person wanted him dead. They learn that Custer and the Seventh aren't what they're purported to be, either. Custer is a self-obsessed glory hunter, spurred on by his ambitious wife; and the Seventh, far from the elite unit depicted by the press, is filled with men who can barely ride or shoot. When Lysander and Verity start coming up with questions Custer doesn't like, Custer tries to remove them from the case. That's his first mistake . . .