Early one morning, a room service waiter at the Rodney Hotel in New York City is horrified to discover that the young man to whom he has just delivered breakfast is standing on the narrow ledge outside his fourteenth-floor room. When the youth threatens to jump, the waiter notifies the hotel manager, while Charlie Dunnigan, a policeman patroling the street below, sees the man and alerts his precinct. Dunnigan then rushes up to the room, and, while sitting on the window ledge, pretends to be a fellow hotel guest. The man refuses to come in, however, and when Deputy Chief Moksar arrives, Dunnigan is dismissed. Back on the street, reporters stream into the hotel, and Dunnigan tries to manage the crowd of bystanders and snarled traffic. While Dunnigan advises a woman named Mrs. Louise Anne Fuller to leave her cab and walk, a young woman named Ruth discusses the drama with a fellow watcher, Danny Klemptner. In the hotel room, Bellevue psychiatrists Dr. Strauss and Dr. Benson tell Moksar that the youth, whose name they still do not know, refuses to talk to anyone except Dunnigan, and Moksar sends for him. Meanwhile, as television and radio reporters broadcast the event, Mrs. Fuller reaches her attorney's nearby office, where she and her husband are to finalize their divorce agreement. A fervent evangelist, the Reverend Dr. J. C. Parkinson, then tries to gain admittance to the hotel, but a policeman shoos him away as Dunnigan arrives. Strauss and Benson advise the nervous Dunnigan to act natural and keep the boy talking, and soon Dunnigan and the young man are chatting about the upcoming St. Patrick's Day parade. Through his fingerprints, the police learn that the youth is Robert Cosick, and try to find his divorced parents. The police locate Robert's mother, but her hysteria only upsets Robert further. Mrs. Cosick relates that Robert, always a nervous boy, had been hospitalized for his condition. Mr. Cosick then arrives, and the enmity his ex-wife feels for him embarrasses the policemen. Mrs. Cosick rushes to the window and tells her son that no matter what "Virginia" thinks, he is not sick. Dunnigan is intrigued by the reference to "Virginia," but Robert denies knowing anyone by that name. Mr. Cosick approaches Robert, but the youth is reluctant to confide in him, as they have been virtual strangers for the past fifteen years. Below, Danny and Ruth continue to talk while Parkinson sneaks into the hotel stairway. As Mrs. Cosick informs the reporters about the career she gave up to have a family, Dunnigan interrupts her and learns that Virginia Foster was Robert's fiancee. On the roof, the police build a winch to lower a man down to Robert, but people in a neighboring building alert Robert as the policeman approaches, and Robert threatens to jump. Meanwhile, Mrs. Fuller, who can see the ongoing drama from the attorney's office, tells her still-loving husband that she is tired of the divorce proceedings and would rather stay married. At the hotel, Robert yells at Dunnigan for attempting to trap him, but Dunnigan reiterates that the policeman was trying to help him, and that the city has been brought to a standstill by his suicide threat. Robert apologizes, and Dunnigan persuades him to talk to his father again. Dunnigan then convinces Robert that everyone will leave the hotel room so that he can rest, but as Robert steps in, Parkinson bursts in and frightens Robert back onto the ledge. As night falls, the police locate Virginia and bring her to the hotel, where Strauss and Benson tell her that it was his parents' divorce and Mrs. Cosick's smothering that caused Robert's instability. Although Robert does not want to see Virginia, she comes to the window and states that she still loves him. Dunnigan then promises to introduce Robert to his wife and take him fishing. Just as it seems that Robert is about to come in, a boy on the street accidentally turns on a spotlight that blinds Robert, and in his panic, he falls from the ledge. As he falls, Robert grabs a net that the police had stealthily been raising, and he is pulled to safety. Strauss and Benson sedate Robert and put him to bed, then assure Virginia that the worst is over. Exhausted after his long ordeal, Dunnigan returns to the street, where he is greeted by his wife and son. Later that night, Danny and Ruth, who have fallen in love, walk the street hand in hand.