Professor Henry Barnes, a widower who has been retired from a Midwestern university for eight years, telephones his close friend and fellow chamber music performer, law professor Edward Bell, and asks him to come see him. Henry explains that he needs help preparing his will as he intends to commit suicide. Although Edward rushes over and tells Henry all the reasons why he should not take his own life, Henry continues to feel he no longer is of any use to society. Edward points out that Henry has a lifetime of knowledge to impart via his writings, but Henry declares that when he completes his latest book in three weeks, he will do away with himself. When Edward relates this to his colleagues and fellow chamber music players, they are horrified. One of them, Philip Conway, a medical doctor, arranges to examine Henry and finds him in excellent health and not depressed or bitter. Henry tells Conway that he had a wonderful marriage and, although their son was lost in the war, has had a full and satisfying life. Henry claims that he has not been sleeping well and asks Conway for sleeping pills, but the doctor gives him only two. Later, while Henry is feeding pigeons in the park, young Peggy Taylor sits down on the bench beside him. She tells him that she and Jason, her husband who is studying chemistry on the G.I. Bill, have been looking for an apartment and are expecting a baby. Henry offers to mention their predicament to Edward, who is also the university housing administrator. After a philosophical conversation with Peggy about the pros and cons of suicide, Henry ponders whether he is really "living now." When Edward reveals that during the war two soldiers were temporarily billeted in Henry's attic, the effervescent and determined Peggy goes to Henry's house and talks him into letting her and Jason move into his attic. The couple causes some havoc in Henry's life, blowing fuses, interfering with his writing and adopting a dog, and Henry finds himself calling Philip for more sleeping pills. Peggy and Jason invite Henry to see what they have done to the attic, and he is amazed by the transformation. Over a cup of tea, Jason tells Henry he wants to be a teacher. Later, Peggy does some household chores for Henry and tells him about the gulf in education between G.I. husbands and wives. Peggy maintains that the wives need overview classes so that they can help their husbands, and has suggested to the university that Henry organize such courses. He protests, saying he wants to finish his book but, a few days later, finds himself in a converted Quonset hut in front of a large group of students' wives presenting a lecture on the basics of philosophy. The class is very successful, and Henry takes a new lease on life. When Jason discovers that Peggy hasn't been taking vitamin pills because they don't have enough money to buy them, he talks about quitting school and getting a job. As Jason is telling his chemistry professor that he is going to have to leave school, he is summoned to the the hospital and learns that Peggy has given birth prematurely and the baby has died. While Jason and Henry walk home, Jason asks him, "Why?" but Henry cannot answer. Later, when Henry visits Peggy in the hospital, he finds her in good spirits and tells her that a life wasn't lost, but merely exchanged, as she has saved him from suicide. Jason then leaves for Chicago to take a job selling cars, intending to send for Peggy later. Henry goes to see him at the used car lot and informs him that he can be reinstated and given a job as a teaching assistant, but Jason feels that a teaching job will not be enough for him. Back home, Henry discovers that Peggy plans to go to live with her sister. Unknown to Henry and Peggy, Jason has returned to take the make-up exams and, with the help of Henry's colleagues, passes all but still has to face chemistry. After Henry grows very despondent because Peggy and Jason are apart, and downs several of Philip's pills, Peggy tells his friends that he has taken a a lot of sleeping pills. The doctor, however, informs them that what he prescribed were not sleeping pills but pills that will merely make him slightly uncomfortable. Meanwhile, Peggy is walking Henry back and forth and filling him full of coffee when Jason comes home. Henry explains that he took the pills because they are leaving him. Jason challenges Henry to pull himself together by saying that he can think of many fellows, including Henry's son, who would like to have had the choice he has now. Moved by Jason's words, Henry gets up and starts walking on his own. Later, Henry changes the living arrangements in the house to give the couple more space. The chamber music group is performing once again in Henry's parlor when Peggy and Jason announce that they are going to try to have another baby.