At Emery Motors in Los Angeles, new company publicist Jane Mitchell is almost as impressed with the plant as engineer Frank Lawson and test driver Terry Martin are with her. While Terry and Frank take her on a tour of the factory, Jane learns that Terry is trying to perfect a new carburetor with Clarence Maxmillian Haggerty, known as "Gadget," his mechanic, and is adamantly against any interference from trained engineers such as Frank. A few days later, Terry invites Jane to a company dance, but she refuses because she has too much work. When she also refuses Frank for the same reason, though, he says that he told another woman that he couldn't go to the dance with her because he was taking Jane. Wanting to help Frank out of an embarrassing situation, Jane agrees to go with him. Josephine "Jo" Sanderson, a former secretary who is now an executive and the woman who asked Frank to escort her to the dance, is in love with him, but his feelings have cooled toward her since her advancement. At the dance, Terry assumes that Jane lied to him about having too much work, and she feels guilty. She then decides to help him without his knowledge and arranges for company president Mr. Dean to finance his carburetor. Dean agrees, but only on the stipulation that a qualified engineer helps. Frank is assigned, and he and Terry uneasily work together. When they are at a stage where Frank thinks that they are ready, Mr. Dean agrees to let them enter the Indianapolis 500 race to test the new design. Terry doesn't think they are ready, but reluctantly agrees. After the trials, Terry is still concerned, but Frank insists that everything is all right, and Terry drives in the race. Something goes wrong, however, and they crash, leaving Gadget critically injured and Terry hospitalized with a concussion. A bitter Terry lashes out at Jane, who realizes how much she cares for him, but cannot make him understand that she has tried to help. He accuses her of only being out for the money and prestige he would have gotten if he had won the race, and sends her away. Soon Terry is back at work, but the company will no longer finance work on the carburetor. Jane then secretly appeals to company owner Emery, whom no one but Mr. Dean knows is her uncle, and they agree to finance Terry's attempt to break the land-speed record. Some time later, at Medoc dry lake, everyone watches as Terry goes down the track and swerves off after completing the first half of the course. By rules of the contest he must complete the return trip within thirty minutes, which now seems impossible. Frank and the others rush to the car and find that Terry has almost been asphyxiated and urgently needs a doctor. Frank puts Terry back in the car and races back down the length of the course, not stopping until he arrives at the hospital in town. When Terry awakens, he learns that Frank's quick action not only saved his life, but earned the new land-speed record for the car. Terry also learns that Jane is really the heiress to Emery Motors and has been secretly helping him all along. Realizing that Jane and Terry are in love with each other, Frank calls the delighted Jo and suggests that they drive back to Los Angeles together.