Learning that Maxwell, the millionaire munitions manufacturer, has the apartment adjoining theirs in the hotel, Mona and Mary seek his aid in furthering their plans for social reforms. He agrees, but postpones action until the arrival of his secretary. That afternoon the girls overhear two brokers quarreling with Maxwell outside his door and threatening revenge. Mary follows the brokers, who go to the writing room. When they leave after writing a note, Mary stealthily secures the blotter they use, and back in the room, the girls find by putting it before a mirror that they have half of an address. The next day they learn that Maxwell has appeared, and that his stock is tumbling. The girls put their wits to the task and finally learn that the complete address on the blotter that of Dr. Walter Ludlow, at a sanitarium near the city. Mona goes to the sanitarium and makes arrangements for them to receive Mary, who, she declares, has become mentally unbalanced. While there she succeeds in confirming her suspicions that Maxwell is held a prisoner. By a clever ruse the girls then succeed in maneuvering his escape and also in bringing Wentworth and his partner and Dr. Ludlow to justice.