Staff members at New York's Blair General Hospital happily prepare for the marriage of resident doctor James Kildare to nurse Mary Lamont. Dr. Leonard Gillespie, Jimmy's wheelchair-bound mentor, is happy for his protégé, but at loose ends because the marriage will mean that Jimmy will have less time to spend with him. Trying to find something to do, Gillespie goes to a concert and observes that the conductor, maestro Constanzo Labardi seems to be faltering. When a mutual friend introduces Gillespie to the conductor, Gillespie suggests that the maestro see a doctor. The next day, Labardi goes to see Gillespie and confesses that he is going deaf, but no one knows his secret. Hoping to cure Labardi, Gillespie, who may have cancer, refuses to accompany cancer specialist Dr. Lockberg to his clinic. While Jimmy and Mary attend a wedding rehearsal at his parents' home in Connecticut, Dr. Lockberg calls Jimmy and asks him to use his influence on Gillespie. Jimmy returns to Blair and convinces Gillespie to go to Lockberg's clinic by threatening not to take his own honeymoon. For the next few days, while Jimmy works with Gillespie on the Labardi case, Mary makes wedding preparations at the Kildares' home. Jimmy is still too busy to attend his bachelor dinner, so Mary, who does not want to disappoint his friends, decides to go in his place. On the way to the restaurant, as she daydreams about her marriage, she accidentally walks into the street and is run over by a truck. When Jimmy arrives at the hospital, he is told about Mary and rushes to her room moments before she dies. One month later, Gillespie is is ready to leave Lockberg's clinic and receives a call from Jimmy's father, Dr. Stephen Kildare, who tells him that Jimmy has not returned to Blair and has fallen apart after Mary's death. Gillespie asks him to relay a message to Jimmy to meet him so that they can talk about Labardi. At Gillespie's childhood home, he tells Jimmy the story of a composer named Cornelia, whom he loved many years ago, before her death. Dr. Walter Reed, the physician who discovered a cure for yellow fever, inspired Gillespie to go on with his career instead of living only for his grief. Jimmy still thinks that he cannot continue, but he agrees to come back to Blair for one week to help cure Labardi. Jimmy soon discovers that Labardi's hearing problems are caused by a Vitamin B1 deficiency, and after injections of the vitamin, the conductor is able to perform a symphony written by Cornelia on the first of his planned series of radio broadcasts intended to bring great music to the common man. After the concert, Jimmy finally realizes that he must return to medicine.