This is the dawn of the Great War. Young Ronald Ewart is ready to enlist in the army, but before that he goes to Scotland to visit his bride, Myra MacLeod. During fishing together, Myra inexplicably loses her sight after she saw a green blinking light. Her father also has a strange experience, and then the faithful dog of Mira will also go blind. They turn to the leading eye specialist, who seems to be an amateur detective, and he takes on the task of uncovering the secret of the green ray....