Mr. Prettyman plans to go to a gay French masquerade ball without the knowledge of his wife, so he writes her that business will detain him so late at the office that he will not be home that night. Mrs. Prettyman's disappointment is great, for she has two tickets for the same ball. Her maid finally persuades her to go alone to the ball. At the ball Mr. Prettyman becomes infatuated with a graceful columbine and Mrs. Prettyman with an audacious devil, neither reckoning on the identity of the other. A flirtation is interrupted by two policemen, who arrest Prettyman, thinking that he is Slippery Sam, a sneak thief. Prettyman escapes, and as he flees in his devil's costume, he spreads terror. Prettyman finally arrives home and the maid slams the door in his face. Then Mrs. Prettyman arrives, and after their surprise, each accuses the other of duplicity. With his inventive genius, however, Prettyman succeeds in straightening matters out.