When the metropolitan newspaper The Bulletin is bought by publisher D. B. Norton, he changes its name to The New Bulletin and replaces its motto, "A free press for a free people," with "A streamlined newspaper for a streamlined era." As part of the new streamlining efforts, managing editor Henry Connell fires "sob-sister" columnist Ann Mitchell because she does not produce enough "fireworks" to bring up the paper's circulation. However, Ann resolves to fight for her job by writing a phony letter to her column, claiming to have received it from a man protesting the degenerated state of affairs in the world and announcing his plans to jump from the roof of City Hall at midnight on Christmas Eve. She signs the letter "John Doe," and its publication results in an explosion of public interest in the fictitious man. Mayor Lovett, who is sensitive about the publicity a suicide from City Hall would generate, publicly offers the mysterious John Doe a job to prevent the suicide, and marriage proposals begin to pour in from concerned women. As a result of the overwhelming interest in her creation, Ann is able to convince Connell that The New Bulletin should continue to print stories about "John Doe" or be forced to admit fraud. Ann is quickly reinstated at the paper, with a thousand dollar bonus, and the search begins for a real person they can use as their John Doe stooge. After reviewing a number of derelicts who have shown up at the paper claiming to have penned the original suicide letter, Ann and Connell decide upon a former bush league baseball pitcher named Long John Willoughby, who is in need of money to repair his injured arm. The naïve John is hired for the job and treated to expensive gifts by the paper, while his hobo friend, The "Colonel," voices his disapproval of the arrangement and tries to warn him about the dangers of becoming one of the "heelots" who, like a lot of heels, sacrifice character for comfort and wealth, and lose compassion for those less fortunate than themselves. No sooner does the John Doe ideal gain widespread notoriety, than the unscrupulous Norton plans to use its potential to further his political goals. Norton commissions Ann to write a radio speech for John, paying her generously for the effort, but she anguishes over the content of the speech, until she finds inspiration in the idealistic writings of her father's diary. Before John makes his speech, however, Mike, an emissary from The Chronicle , Norton's chief competitor, tries to persuade the baseball player to expose the hoax by telling him that if he continues the scam, his baseball career will be over. John considers this, but despite an offer of five thousand dollars and a guaranteed hasty exit from the performance, he tremblingly reads the speech written by Ann, with whom he is infatuated. Later regretting the incident, John and The Colonel flee, but Ann and Norton quickly catch up with them in Millville, where Ann asks John to hear out local members of one of the newly formed John Doe Clubs, hoping that they will convince him to go on as their spokesman. John agrees to continue after being moved by the sincerity of a local John Doe Club chapter leader, Bert Hansen, who tells a heartwarming story about how the movement has been a true inspiration for him and his neighbors. While John, who is now in love with Ann, seeks advice from her mother about how to propose to her, Norton showers Ann with expensive gifts and coerces her into persuading the baseball player to announce the creation of a new political party, which the publisher plans to exploit as a stepping stone to the presidency, at the planned John Doe convention. Disillusioned by the whole affair, Connell gets drunk and exposes Norton's plans to take over the minds of the American people to John, who immediately marches over to Norton's, where he finds Ann and Norton's cohorts meeting to decide the future of the John Doe movement. After upbraiding them for their misdeeds, John announces that he plans to reveal the truth about Norton and his sinister plot at the convention that evening, and then storms out. Ann rushes after him to explain her unwilling involvement in the plan, but John refuses to listen, and police detain her until after the convention. That night, John is outwitted by Norton, who foils his attempt to expose him by distributing printed propaganda that portrays John as a fake and cutting the microphone wires before he can explain the situation. The crowd turns on John, and he is forced to leave and go into hiding. John mulls over the debacle and decides that the only way he can redeem himself is by making good on the suicide promise and thus proving his sincerity and devotion to the cause. On Christmas Eve, the now ill Ann, The Colonel, Connell and Norton intuitively gather on top of City Hall and wait for John to show up. John emerges from the darkness just before midnight, and, as he prepares to jump, Norton tries to stop him by telling him that the act will go unnoticed by the public, because he has made arrangements to have his body removed immediately after impact. Ann pleads with John to reconsider, but he appears resolved to go through with it until a delegation of John Doe Club members arrive and persuade him not to jump by convincing him that they had always believed in him and his good intentions. With his faith in the goodness of the human spirit restored, John leaves the rooftop carrying Ann, who has fainted, in his arms.