Blind detective Duncan Maclain is visited by old friend Norma Lawry, looking for help in getting rid of one of her old beaus, who is courting Norma's 17-year old step-daughter. When the old beau is found murdered, Norma is the chief suspect until Duncan (aided by his guide-dog Friday) pays a visit to her home and uncovers a plot to steal her husband's military secrets for the enemy.