In 1875, Detective Lysander Hughes is hired by Colonel George Custer to investigate the murder of an officer in the Seventh Cavalry. Lysander goes undercover as an enlisted man to find the killer, who is believed to have been one of the officer's men. He discovers that the vaunted Seventh Cavalry is not the elite regiment that the papers make it out to be, and that a large number of its officers and enlisted man despise their famous commander. Lysander reluctantly teams up with a pioneering female newspaper reporter named Verity Winslow. Lysander and Verity mix like oil and water, but Verity has information that's important to the case and she won't share it unless Lysander agrees to let her help. As the two of them dig deeper, they start to believe that Custer may not want them to find the real killer . . .