In a Korean prisoner-of-war camp, Dr. Adrian Carmichael is struggling to keep his fellow prisoners alive despite the lack of medicines and facilities. After a prisoner dies in his arms, Adrian assaults the brutal camp commander and is whipped unmercifully as punishment. During an air attack on the camp, Paul Quentin, Adrian’s friend, tries to comfort him as he lies dying from the whipping. Adrian has received a letter from his wife Alice, in which she confessed that she had been unfaithful to him and sought his forgiveness. With his dying breath, Adrian makes Paul promise not to let his young children, Johnny and Libby, be raised by another man and emphasizes that they would be better dead than with any father other than him. Adrian dies as a bomb lands nearby, but Paul and the other prisoners escape. Months later, after Paul is treated for shell-shock trauma in the psychiatric ward of a veterans administration hospital, a doctor tells him that the committee feels that he is now able to begin to rejoin society and offers him a weekend pass. Paul, a former classical pianist with no relatives, decides to take a bus to visit Adrian’s family in a small town. Adrian had told Paul so much about his father James, mother Mary and eighteen-year-old sister Meg, that Paul feels that he already knows them. They give him a very warm welcome and invite him to stay with them for the weekend. James is in a wheelchair as the result of a stroke suffered upon learning of Adrian’s death and Alice, who lives nearby, has taken over the management of the family's bookstore. In the evening Alice comes over and Paul talks with them all about his friendship with Adrian and how the prisoners regarded him as a sort of saint. Later, after Alice asks to speak with Paul in private and they drive to her house, he reveals that Adrian received her letter just before they were captured and never spoke of her again. Alice explains to Paul that she has ended her very brief affair with the man, Howard Gray, and that Adrian’s family knows nothing of her indiscretion. Paul promises not to tell the Carmichaels about it and agrees to return the next day to meet the children when they return from boarding school. Unknown to his doctors, Paul has become obsessed with keeping his promise to Adrian that Johnny and Libby will never be reared by another man and, while he walks back to the Carmichaels’ house, he hears Adrian’s voice asking him to send the children to him. On Saturday morning, after Mary and her housekeeper remark that having Paul there is almost like having Adrian back, Paul and Meg go swimming. Meanwhile, Alice is consulting her lawyer friend, Parry Sanborne, because Gray is blackmailing her and threatening to reveal their affair to the Carmichaels. Later, as the result of Paul’s calming visit, James is able to leave his wheelchair and, after asking Paul about his plans, invites him to join the bookstore business as his son. Traumatized by his pledge to Adrian, Paul breaks down then goes to meet Johnny and Libby who like him immediately and take him on a tour of their play areas. While inside a spring-house, a small stone building built to protect a natural spring, Paul almost succumbs to the temptation to drown the children. That night, Mary encounters Paul sleepwalking in the house and muttering, “Please, Adrian, I can’t do it.” Invited by Alice to take Johnny and Libby to Sunday school, Paul collects the children and on their way to the church, they stop once again at the spring-house. Although, in one part of his mind, Paul is aware that there is no man in Alice’s life, he cannot escape the obsession of his commitment to Adrian and believes that he must kill the children. Leaving them beside the spring, Paul goes to look for a weapon and returns to Alice’s kitchen for a knife. Meanwhile, Gray has come to the house demanding more money and threatening to talk with Alice’s father-in-law about her and her children's future. Paul overhears the fight and, assuming that Gray wants the children, attacks him with a knife. After a struggle for possession of the weapon, Gray knocks Paul down a flight of cellar stairs then runs off. Later, Paul recovers and realizes that the shock of the concussive fall has released him from the obsession to honor his promise to the dying Adrian. Everyone is relieved by Paul’s recovery, and although he has to go back to the veterans' hospital, he promises Alice, Meg and the others, that he will return to them.