Martin Wright, American manufacturer of ammunition and weapons, determines to profit by the war in Europe and sends David, his only son, abroad to represent the firm and promote the sale of his products. The young man sends back word that he has interested the representatives of two great powers, and that special envoys will call upon the manufacturer and draw up contracts with him. Wright, the maker of guns, is elated. He tells Dolly, his daughter. But she does not share his enthusiasm. In due time, the guns are sold and sent abroad. As time passes, however, the manufacturer becomes uneasy about his son. At last. David's valet returns alone. The son, his father now learns, for the sake of Leonie De Lisle, with whom he had fallen in love, while abroad, has enlisted in the French army. The valet also had volunteered, in order to be near his master. During an attack on a certain fort, guns of great power, bought in America, swept away their company. David Wright was among the first to fall. "Fort Z----," repeats the maker of guns dully, "Those were my guns which killed my boy."
—Moving Picture World synopsis