A sophisticated reporter hires the construction worker she accidentally got fired.

Renowned New York photographer Katherine Grant feuds with the managing editor of Mirror magazine over the content of her photographs, which tend to be more artistic than commercial. When she is assigned to photograph the Interborough Vehicular River Tunnel project, she dons a hardhat and boots and goes deep underground. The superstitious tunnel workers, called "sandhogs," fear that a woman in the tunnel will bring bad luck. Katherine's distracting presence causes a nearly fatal accident for Jim Ryan, a self-assured, brawny sandhog nicknamed "Superman," who is almost crushed by a machine because Katherine insists on taking his picture. Katherine drags an unconscious Jim out of harm's way, but their work disrupted, the sandhogs are dismissed for the day. When he revives, Jim feels disgraced that a woman saved his life, and while in the compression chamber, he gets embroiled in a fistfight with his taunting co-workers and is photographed by Katherine. Jim later accuses Katherine of flirting with him, and although he is right, she coldly tells him that her boudoir chair has more integrity than he does. Katherine develops the photographs and shows them to her sister Hoppy, calling Jim an "ape." She also shows the pictures to her snobby sophisticated friends, including Mirror publisher Henry Fulton, her suitor, playwright Dunbar, and Roger, a composer, who are delighted by her foray into the blue-collar world. Jim, piqued by Katherine's previous insult, returns her tripod to her at her apartment, and regains his confidence after he kisses her and then dismisses her. When Katherine's friends eagerly ask him to describe his fistfight, Jim demonstrates and knocks out Henry. For weeks afterward, Katherine finds herself plagued by dreams in which Jim appears as a "superman" and rescues her from an evil suitor. Jim is suspended from work after Henry publishes Katherine's pictures of the fistfight, which he stole from Katherine. After assuring Jim that she had nothing to do with the publication of the photo, Katherine hires Jim to be her assistant, hoping to prove to herself that he is not worthy of her love. Instead, Katherine falls in love with Jim, but he dumps her when he finds out from Hoppy about Katherine's true intentions. Sometime later, a cave-in interrupts the tunnel project, and Jim, an engineer by training who was working as a sandhog only to better understand the project, conceives of a plan to save the tunnel. Katherine is assigned to report on the trial run of Jim's newly invented machine, and returns to the tunnel along with a host of other reporters. Katherine resents being kept a safe distance from the work with the other reporters, and sneaks further into the tunnel, where Jim and his assistants make a trial run with the machine. While Katherine photographs the machine at work, a breach in the wall results in a mudslide, and she is buried underneath. The sandhogs abandon the machine to save her, and Jim's test run is declared a failure. Katherine convinces Roger, and Jim's friend Clancy to return to the muddy tunnel to find her camera, because her pictures will prove that the machine was actually working. They successfully retrieve the camera from the thigh-deep mud, and as a result of the photographs, the city reinstates Jim and reopens the tunnel project. Katherine insists that Jim never know she was responsible for his reinstatement, and becomes engaged to Fulton. Roger tells Jim the truth, however, and warns him that she is marrying Fulton even though she still loves Jim. That night, Darlene, a showgirl that Jim has been dating, interrupts Katherine's engagement party to warn her to stay away from Jim, and when she slaps Katherine, Katherine punches back. Jim arrives in time to witness Katherine's spunk and asks her to choose between him and Fulton. When she chooses Jim, he proudly carries her out over his shoulders.