On their fourth anniversary, eccentric architect Steve Ireland and his wife Susan anxiously look forward to reliving their wedding night, but their plans are ruined when Susan's mother, Mrs. Cooper, shows up and asks Steve to mail a letter for her. On his way back up to the apartment, he runs into Isobel Grayson, a now married ex-girl friend, who has moved into the apartment below. When the elevator gets stuck and they are forced to climb out of the car, Steve gets a concussion. Isobel then takes him to her apartment for a drink and tries unsuccessfully to rekindle some of their old romance while her artist husband "Pinky" is working in his rooftop studio. Steve returns to his own apartment and relates the elevator problem but doesn't mention Isobel until he has to explain how his hat got into her apartment. Everything seems fine again until Mrs. Cooper starts to leave, slips on a rug and sprains her ankle. Susan then has to go in her mother's place to meet a relative at the train station while Steve stays with Mrs. Cooper. He goes on the terrace for air and sees Isobel, who invites him down for a drink. He agrees, unaware that Mrs. Cooper, who has eavesdropped on their conversation, will gleefully tell Susan upon her return. Hearing this, Susan calls Pinky and suggests that the two of them meet to make Isobel and Steve jealous. Susan then mistakenly goes to the apartment next to the Graysons' and finds Ward Willoughby, a handsome, if perplexed world champion archer who is happy to cooperate with her apparent desire for romance. Just as Susan and Ward realize the mix-up, Steve, Isobel and Pinky arrive, and all retreat to their respective apartments after some noisy arguing. Although Susan and Steve decide to forgive and forget, when a cab driver calls for Steve, Susan assumes that he has been lying about going out for an innocent drink and concludes that he was in Isobel's apartment the entire evening. The next day, their lawyer, George Renny, summons Steve to his office because Susan wants an immediate divorce. Because George won't represent her, Susan goes to another lawyer, disregarding Steve's plea that she is "convicting" him on circumstantial evidence. Susan then disappears until the night before their divorce hearing when George calls to tell Steve that Susan is at a party he is attending. Steve crashes the party, but only makes matters worse when he tries to get her to reconsider. After she leaves, George tells Steve that Ward has been in Arizona with Susan and her mother. The worried Steve now begs George to have the hearing postponed, but George says that nothing short of his insanity would work. Steve decides to feign insanity and, needing witnesses, tells one bearded guest that he hears voices, then says he is Abraham Lincoln and throws all of the men's top hats into the pool to "free" them. Everyone thinks he is drunk, except for the bearded guest, who is concerned. At the divorce hearing, George argues that Steve is crazy, but Susan testifies that Steve's eccentricities are merely jokes. When Steve shoots paper airplanes at the judge, however, the case is adjourned for thirty days to have Steve's sanity determined. Knowing what Steve is up to, Susan convinces the judge to have Steve appear immediately before the city lunacy commission. Now realizing the seriousness of his actions, Steve goes before the board and acts normally until the commission head, Dr. Klugle, arrives and Steve recognizes him as the bearded man at the party. Steve is so unnerved that he appears completely incompetent and is declared insane until his case can be reviewed in six months. Susan begs Steve to show them that he is really sane, but when he refuses she agrees to send him to a sanitarium. As the weeks pass, Steve tries everything to escape and finally manages to jump the fence by tricking Dr. Wuthering, the head psychiatrist. Convinced that Susan really does still love him, Steve makes his way back to his apartment building. Because the police are after him, he goes to Isobel to ask for help, then enters his own apartment wearing a dress and wig and pretending to be "Miss Ireland," his sister. Susan agrees to hide him but still insists that she won't take him back. When Ward and Mrs. Cooper arrive, they make disparaging remarks about Steve in front of his "sister," angering Susan, who asks them to leave. When Mrs. Cooper inadvertently confirms Steve's story that he and Isobel really did leave the building the night of their anniversary, Susan goes to Steve for a reconciliation. Finally, when Ward calls because the police have mistaken him for Steve, Steve gives him the raspberries.