Twenty-six-year-old Mary Fanshawe, a dedicated, attractive nurse, is the able supervisor of Ward K in a prestigious hospital. Her judgment in matters of the heart is not as sound as her professional acumen, however, for she is in love with the philandering, ambitious Dr. Preston. As a result, she resents the competition that Dr. Jim Barclay, a brilliant surgeon and protégé of elderly Dr. Walter Selby, presents for Preston. Although grateful to Selby for providing him with the opportunity to work at the hospital, Barclay recognizes that Selby's methods are sadly out of date and may be endangering patients. Meanwhile, Doris Andros, a junior nurse, has become the latest object of Preston's attention, and she dwells on him to the detriment of her work. Mary, not knowing of Doris' affair with Preston, upbraids the junior nurse for her lack of dedication. In Mary's ward are a variety of cases, including Julie, who believes she is recovering, but is about to have a leg amputated; Mrs. Flannigan, who loves her husband all the more for having broken six of her ribs; and Gail Drake, a nightclub dancer, who has been scarred by acid thrown by a rival. The most complicated case is that of "Number 16," who suffers from a brain disorder that Selby is treating by an old-fashioned method that, while avoiding the risk of surgery, multiplies the eventual need for it. Barclay proposes a more dangerous operation that offers the possibility of a complete cure. Selby is finally persuaded to let the surgery by scheduled, but as the patient is being prepared for the operation, which only Barclay is qualified to perform, Selby jealously pulls rank and insists on acting as the head surgeon. During the procedure, Selby loses his nerve, and Barclay must push him aside in order to finish the job. Later, Barclay offers to resign rather than further embarrass his superior, but Selby refuses to accept his resignation, and instead indicates that he will retire and name Barclay his successor. Soon after, the despondent Gail drinks alcohol that Doris has carelessly left behind in an attempt at suicide. Although he is on duty, Preston is on the roof with Doris and cannot be found, and Barclay is called upon to save Gail's life. Barclay attempts to shield Preston before Mary, but Doris admits what happened when she quits. Although disillusioned in love, Mary is encouraged by Barclay's expression of admiration, and a new affection stirs her heart.