As World War I begins, Irish rebels plan to use the British preoccupation with Germany to their advantage. Sir Denis Esmond, an Irish leader, intends to fight the English, while his close friend Leslie St. George Leigh loses his eyesight fighting for England in the North Sea. Denis and Leslie both love Mary O'Neil, an Irish girl, who refuses to decide between them until the Irish question is settled. Mary allows Leslie to convalesce at her family's castle; then, when Irish rebels come looking for Denis, Leslie tries to convince him of the high cost of rebellion. He succeeds, but as Denis is about to address the rebels with an English flag, Mary substitutes an Irish one, and the British eventually battle the Irish and arrest Denis as a traitor. Despite Mary's pleas and those of Denis' mother, he is sentenced to hang. Through the eventual intervention of his friend General Ramsay, however, Denis is pardoned. Leslie, thinking that his blindness will prevent a successful marriage to Mary, withdraws, but she finally makes him realize that even his blindness cannot alter her love, and they become engaged.