Casca returns to the United States to escape from British justice, and becomes involved in saving a family of Irish immigrants from the clutches of an evil brothel owner. Hunted by the Brotherhood as well as the criminal’s associates, Casca opts for the safety of the American army just as war with Mexico breaks out. And Case Lonnergan – as Casca calls himself – soon finds he is fighting in a war where every attack is directed against well defended positions. Teaming up with a unit of Marines, Case becomes part of the birth of a legend, and in front of the forbidding Chapultepec Castle he leads them in a suicidal head-on assault!