A medical student will stop at nothing to become a top surgeon.

Lucas Marsh, an ambitious medical student who rigidly strives for perfection, desperately needs money for his tuition. Luke visits his alcoholic father Job, who has squandered the money that Luke's mother had saved for him. Hurt by Luke's scorn, Job tells him that he will never be a good doctor because "something was left out of him," leaving him with no empathy. Although Alfred Boone, a fellow student, and pathologist Dr. Aarons lend Luke some money, it is not enough. Aarons advises him to return to school after working for a year, but Luke is unwilling to postpone his education. With the borrowed money, Luke makes a partial payment, but is informed that, unless he pays the balance within thirty days, he will be expelled. Later, after Luke and Al watch an operation, shy, Swedish-American spinster Kristina Hedvigson, the head operating-room nurse, invites them to a smorgasbord the following weekend at the home of Swedish-American friends. There, Kris's friend Bruni, who knows that Kris has a crush on Luke, brags about Kris's thriftiness and reveals that she has saved several thousand dollars. The comments are not lost on Luke, who takes advantage of Kris's admiration for him by romancing her. Kris soon admits to Bruni that she is in love with Luke, although she is both worried by and attracted to his dedication to being a doctor. Soon after, Luke asks Kris to marry him, then informs her that he is about to leave school, prompting her to offer him the tuition money. He pretends to be proud and refuses the help, but then "relents." That night, Al accuses Luke of exploiting a woman who is afraid of becoming an old maid and of allowing himself to be kept. Luke insists that Kris will never learn that he does not love her, and Al agrees to be his best man, despite his further admonition that Kris is not sophisticated enough to be a doctor's wife. After Luke and Kris are married, he continues his studies with her help. One day, Luke publicly criticizes a surgeon, Dr. Dietrich, for failing to use a new, proven technique during surgery. Aarons is outraged by Luke's arrogant behavior and, although he admits that the surgeon was wrong, tells Luke that he will not be allowed to intern at the hospital unless he apologizes. Luke refuses to give in and implies to Kris that she is too stupid to understand his dogmatic view that a doctor must be perfect at all times. The following day, however, Luke reluctantly apologizes to Dietrich. Time passes, and after becoming interns, Luke and Al are on duty one night when an ambulance brings in the dead body of a man who fell under a bus. The dead man turns out to be Job, and Luke, showing emotion for the first time, cries for his father. Some time later, when Luke discovers that Al has carelessly removed a patient's mole that Luke had earlier recognized as a melanoma and refused to touch, he threatens to report the incident, but Al does so himself. Kris criticizes Luke for yelling at Al, his best friend, in front of others, but Al later admits that Luke was correct to reprimand him. After completing his internship, Luke takes a position in the small town of Greenville as assistant to general practitioner Dr. David W. Runkleman. Luke works hard and learns a great deal from the practical but compassionate Runkleman. Believing that it is time for them to start a family, Kris attempts to broach the subject to Luke, but he falls asleep while she is talking. Luke soon meets a wealthy and sophisticated young widow, Harriet Lang, who breeds horses, and is immediately attracted to her. The next morning, while testing a new stethoscope on Runkleman, Luke discovers what Runkleman has known for some time, that he has a serious heart condition. Luke advises him to retire, but he refuses. When they then perform an operation, Dr. Clem Snider, director of the local hospital who serves as the anaesthetist, almost causes the death of their patient. Later that night Runkleman tells Kris and the still-brooding Luke that Snider is a political appointee and cannot be replaced. During dinner, they meet Harriet and her lawyer, Ben Cosgrove. Luke gets into an argument with Cosgrove, and later, at home, argues with Kris because she drank too much and was jealous of his attentions to Harriet. Although Luke apologizes, Kris realizes that their marriage is crumbling and asks him again about starting a family, but Luke tells her that he is not ready. Later, despite Harriet's warning that she cannot afford to fall in love with Luke because he would have no time for her, they start an affair. Meanwhile, Kris goes to see Al, who confirms that she is twelve weeks pregnant. Kris reveals that she has not told Luke, and Al, who realizes what a wonderful wife Kris has been to Luke, advises her to do so. Later, at the hospital, Luke discovers that Mr. Carl Emmons, an elderly patient Snider has left to die quietly, has typhoid but can be saved. After Luke puts Emmons in isolation and threatens to kill the incompetent Snider, he asks Kris to help him and, together, they save Emmons. Genuinely admiring Kris's nursing abilities, Luke tells her that she should return to work and that a family is not for her. When Al comes to visit soon after and finds Kris alone because Runkleman and Luke are innoculating the townspeople against typhoid, he urges her to tell Luke about the baby. Meanwhile, Luke visits Harriet and tells her that he feels guilty and must end their relationship. When Luke returns home, Al is waiting outside and tells him about Kris's pregnancy. Stunned, Luke apologizes to Kris and asks for another chance, but, realizing that he has always used her, Kris angrily rejects him. Later, Runkleman collapses due to his heart condition and Luke operates immediately, ordering Snider to assist. They repair Runkleman's ruptured aorta, but when Luke attempts an added procedure, he makes a miscalculation that causes the aorta to rupture again and Runkleman dies. As Luke leaves the operating room, Snider says, "God help him, he made a mistake." Distraught, Luke walks through town and at last realizing his own humanity, returns home to Kris, who welcomes him with open arms and comforts him.