Young Dan Talfourd and Lucy Winter are sweethearts. Old Talfourd and Dan quarrel over their stenographer, Anna, because of the manner in which she seems to boss the elder man. The latter tells Dan that the matter must not be spoken of again. He is stricken and taken home mortally ill, Dan goes home and his father makes a dying confession. He tells Dan that Anna is his sister, an illegitimate daughter by another woman. Dan is compelled to promise his father that he will take care of Anna. Anna and Dan swear to keep the matter a secret. Lucy, suspicious of the intimacy that seems to exit, tells Dan he must discharge Anna. Dan cannot do this and the engagement is broken. Later at a masked ball, Dan goes as Faust, Lucy as Marguerite and Anna as Carmen. Nobody knows who anyone else is, so that when some of the maskers think that it would be great fun to hold a carnival mock marriage, with Faust and Marguerite for the principals, they are seized and placed before another masker attired as a Lord Chief Justice. All three principals try to back out, but the fun-makers will have nothing else, and they go through the ceremony with carnival spirit. At the unmasking Dan and Lucy are deeply angered to find that they were the figures in the ceremony and though Dan is agreeable to forget their quarrel, Lucy will not have it. Anna, who has unmasked with the rest, but not as yet been seen by either Dan and Lucy, goes after him and tries to cheer him up. Lucy at that moment also seeks Dan, having changed her mind, but seeing Anna there in an attitude of familiar friendship, she cuts him completely and accepts the attention of an old admirer, Dave Bennett. The next day Mowbray, the man who had masked as the Lord Chief Justice, comes to Dan and shows him that the ceremony was valid, as that day he had been ordained a minister, but not opening his mail, did not know about it until after he returned home. Anna has overheard the conversation and is pleased at the double hold he now has over Dan. Dan tries to regain Lucy’s affections, but finds Bennett always with her. Lucy, jealous and angry, sees Anna with an unscrupulous chap named Dawson, who is taking her into a café of ill repute, so when she meets Dan a short time after he tells him about it, thinking to break down his seeming infatuation. Dan leaves her and goes in search of Anna. He finds them in the café, where Dawson is trying to get her to drink. There is a fight when Dawson resents Dan’s interference. Lucy reads of the brawl in the papers the next day and her anger toward Dan deepens to such an extent that she accepts Bennett. Dan is about to tell her about the validity of the marriage when he realizes that she must care more for Bennett than she does for him. She tells him she does and on the day set for the wedding Dan decides to shoot himself at the hour of the ceremony, so that the way will be clear for her to be happy. Anna with the paper Mowbray signed breaks in upon the ceremony and makes clear Lucy’s position. Lucy, overjoyed, hastens with Anna to Dan’s home, where they are just in time to save him from pulling the trigger. Anna now happy, leaves them in each other’s arms.