A spy blackmails a commander's wife into stealing treaty. Colonel Von Harlan [the spy] makes his escape from Mary, the maid after they struggle on the floor. Mrs. Scott-Neville breaks through the door and picks Mary up from the floor. They give chase only to discover that Von Harlan had made good his escape by hansom cab. Mrs. Scott-Neville determines to risk herself to save her husband's honour. She hails a cab and gives chase. Commander Scott-Neville awakens from his drug-induced sleep. He discovers the treaty to be gone. Mary informs him of the situation. He collects his gun and smells the coffee which he realises is drugged. He takes the calling card left by Von Harlan and hails a cab. Von Harlan enters his rooms, he discards his gun on the table and searches in his desk. Mrs. Scott-Neville sneaks into his room and takes the gun. She attempts to force Von Harlan to hand over the treaty but he struggles with her and the gun is fired. Finally, Von Harlan overcomes her. However, the Commander arrives on the scene and a further struggle ensues. They battle each other down the stairs and fall over the bannister. Von Harlan is disarmed but he takes a sword from the wall. Just as he is about to run the Commander through, Mrs. Scott-Neville, who has picked up the discarded gun, shoots him.