The wealthy Endicotts, led by the oldest brother, Edward, contract a steamboat to take their large family, servants and horses, up the Missouri river to establish their business in the new frontier. But their dream ends after a vicious attack on the boat by the Nathan Hawks gang, which includes the brutal brother and sister half breeds, Stone Face and Dark Sky. All of the Endicotts and servants are massacred, except for young, Glory Endicott and the beautiful teacher, Janey Shire who are taken hostage. Soon after, a band of horsemen led by the legendary Texas Ranger, Captain Tully Slay, along with Tyke Flannery, an Irish freedom fighter, Big Robbie, a former slave with a mysterious past, two riflemen, Benny Link and Evan Mooney, and an old Comanche scout, Magpie, follow the gang through Texas into Mexico. By the time they have reached the Rio Grande they are joined by two more Texas Rangers, and a Mexican hostage turned ally. As the Hawks gang waits for the arrival of the horsemen their gang is reinforced with vaqueros from the bandit, Emilio Rios. After the raid at Pueblo de Coyote, only fate, luck and courage will decide who will ride away from the border town. The Horsemen is the first novel in an epic western trilogy, followed by In the Devil's Skin and Children of Thunder.