Expelled from West Point for committing a minor infraction, Royal Macklin, the last descendant of a family whose men fought nobly in America's wars, determines to prove himself as a soldier. Leaving behind his cousin Beatrice, whose father broke off their engagement, Macklin travels to Central America and joins Foreign Legion General Laguerre. Laguerre makes Macklin a captain because of his acquaintance with Macklin's grandfather, a general who before he died, had given Macklin a sword and told him to fight for the honor of the family name. Macklin becomes a strict disciplinarian and develops an effective fighting force. After the revolutionary president Alvarez confiscates property owned by Beatrice's father, she and her father are arrested when they arrive to investigate -- the father, because he has struck an official, and Beatrice, because her beauty attracted the official. The father escapes and notifies Laguerre's headquarters. Macklin leads an attack, retakes the capitol for the deposed General Garcia and rescues Beatrice. Her father then allows them to marry.