On a busy night at Blair General Hospital in New York City, head nurse Molly Byrd returns from a three-week vacation and asks her staff about resident Dr. James Kildare, whose fiancée, nurse Mary Lamont, was killed the day before their wedding. Byrd is told that Kildare has been carrying on only because of his love of medicine. Head surgeon Dr. Leonard Gillespie, Kildare's wheelchair-bound mentor, is also concerned and orders him to take a night off, but instead Kildare accompanies his friend, intern Donald Winthrop, on an emergency ambulance call. During the ride, Kildare advises Donald to propose to his girl friend, nurse Annabelle Kirke, telling him that he himself was wrong to wait. After Kildare revives a suffocating infant on the emergency call, he sends Donald back to Blair. On the way, Donald, who, like Kildare is concerned over a territorial division with nearby Emerson hospital that can cause delays in emergency service, notices an accident and stops, even though it is not Blair's territory. He finds well-known society girl Cynthia "Cookie" Charles lying on the street, gravely injured by broken glass. Over the ambulance driver's objections, Donald takes Cookie to Blair, then, with Annabelle's compliance, omits the pickup address on the admittance card. Kildare performs a delicate operation to remove glass which has pierced Cookie's heart, and is successful. Shortly thereafter, Donald and Annabelle tell him that they are engaged, but are worried that Donald might be fired because of his deception on Cookie's admittance card. They soon hear from Blair administrator Walter Carew that the hospital's board is furious over a protest from Emerson. Gillespie and Kildare plead Donald's case, but the board insists that Donald be fired. Kildare then goes to Cookie and asks her to save Donald by using her influence with the board. Meanwhile, Kildare cures little Helen Johnson, the daughter of a newspaperman, of diptheria. Feeling that he has no chance of remaining at Blair, Donald decides to go into private practice, but has no money. He is at first reluctant to let Annabelle help him by continuing to work after their marriage, but Kildare and Gillespie convince him that he is being silly. That same night, a cab driver rushes to the Blair receiving desk with a gravely ill passenger, but Annabelle refuses to admit him because the fare was picked up in Emerson territory. Not wanting to wait for an ambulance, the cabbie drives the man himself. Meanwhile, Kildare learns from Cookie that despite her best efforts, she has been unable to change the board's decision about Donald. Cookie, who is very attracted to Kildare, says that she lives on only a $90 weekly inheritance that is about to run out and is trying to find a "guy to protect me." Kildare is also attracted to Cookie, but his feelings for Mary prevent him from responding to her. A short time later, Kildare learns from Annabelle that she has been fired for refusing to admit the taxi passenger, who was dead on arrival at Emerson. Determined to help her and Donald, Kildare asks Johnson to write a feature article about their situation and the problem of territorial disputes between the two hospitals. The next day, Kildare is disappointed that the article does not appear in Johnson's paper. He is summoned to appear before Blair board member Baxter, who explains that he had learned about the article before it was printed and arranged for it to be killed. Baxter refuses to rescind either firing and temporarily suspends Kildare for his actions. Now Gillespie determines to help and goes to Cookie for assistance in getting the story out. The next morning, she calls Kildare to her room and shows him a front page story in another paper that relates the incident and adds that a new dispatch system has been set up between Blair and Emerson and Annabelle and Donald have been reinstated. Cookie then is released from the hospital, but tells Kildare that she will be back next week so he can see her scar.