Based on Graham Greene’s novel, during World War II a writer in London falls in love with the wife of a civil servant. She loves him too, but then she has an unusual religious experience.
In London during the war at a party Henry Miles (Peter Cushing) introduces the writer Maurice Bendrix (Van Johnson) to his wife Sarah Miles (Deborah Kerr). Henry sees her kiss a guest goodbye and decides to get to know her. He has a drink with her and kisses her. Walking back, they take shelter during an air raid. He says his limp did come from a wound early in the war. She says she noticed something special, and he takes her to a hotel.
Maurice calls on Sarah, and they embrace and kiss. Later he asks where she was, and she says she was visiting her mother. Henry comes in and says the widows he is working with now are younger. At the door Maurice tells Sarah anyplace but there.
Maurice and Sarah spend time together away from her place. She remembers a romantic moment in the snow and says others besides writers have imaginations too. Mrs. Tompkins talks to Sarah and calls Maurice her husband. Sarah explains to him it would be awkward to correct her. He commends her on her ease at lying. He is upset and feels taken for granted. He is bothered by the uncertainty and the being apart. She says she loves him, and he wishes they could be married and be happy always.
Sarah visits Maurice and finds him typing. He stops working. She mentions God in time of war, and he asks if she believes in superstitions. They kiss and plan to go out for dinner. Later he sees different planes dropping bombs. He tells her to go home, but she says no. He says he will check the basement and goes downstairs. A bomb explodes, and he is buried under a door. He gets up and walks upstairs. Sarah is shocked that he is alive. He asks why she was on her knees, and she says she was praying. She says he was under the door, and she could not lift it. He says he feels like he was on a long journey. They hear another bomb, and she leaves. He wants to see her the next day, but she says it may not be safe. He calls after her, but she is gone.
Maurice sees doctors for seven days, but he cannot get her on the phone. He thinks she has been lying to him.
A year later the war is over. Maurice works hard on his book. He sees Henry and hates him and Sarah. He decides to talk to Henry outside in the rain. Henry says he is worried about Sarah and invites Maurice to his house. In his study Henry tells Maurice he is afraid. Henry shows him a letter recommending a detective. He says he cannot trust her and that she is away at all hours. Maurice offers to go to the detective for him. Henry rips up the letter and throws it in the fire. Maurice remembers the name and address. Sarah comes in and says goodnight.
Maurice consults the detective Savage and finds out how much he charges. He tries to call Sarah and sees her on the street. They talk, and she asks about his writing. He says they can meet as old friends. He asks what happened to them. She says she was to blame. She coughs and says goodbye.
Albert Parkis (John Mills) comes in to see Maurice and makes his report. He works with a boy, and he describes what Sarah did. He says she met a gentleman and walked to her house. He was observing the previous scene with Maurice and then realizes that. Maurice wishes that he had never met her.
Parkis call Maurice to come to a house where Sarah is visiting. Parkis explains how he will determine who. He shows Maurice a letter pieced together from a waste basket. Sarah wrote that she realized they should “be together now and forever.” Maurice goes to the door and reads the names and says it was Smythe. In a phone booth Maurice calls Henry and arranges to meet him at his club
Henry comes into the club, and Maurice asks him if he is still worried. Maurice says he went to see the detective and that Henry was right in his suspicions. He shows Henry the report. He reads it and throws it in the fire. Maurice shows him the pieced-together writing and quotes it. Henry leaves.
Parkis tells Maurice that he crashed the Miles’ cocktail party. He shows Maurice a journal written by Sarah. He says she did not look well. Maurice thanks him and says he will write a report on his work.
Sarah narrates her visiting Maurice when the bomb exploded. She goes down the stairs, but she cannot lift the door off him. She touches his hand and is afraid he is dead. In his room she picks up his papers on the floor and prays to God that he not be dead. She promises to be kind and good and that she will give him up forever. Maurice comes in. She narrates that it was hysteria. She says she will tell him of her promise, and they will both laugh. She sees his fear and leaves. She sees damage. A man says they can pray now because they can’t do anymore for them.
In a church Sarah talks to a priest. She says she is not a Catholic. She says he was not killed, but she thought he was. She says they loved each other and that he was not her husband. She thought she “prayed him alive.” She says she made a stupid promise that was a mistake. He asks what she promised to whom. He says if she does not believe in God, she is free not to keep it. She says if God exists, he put the thought in her mind, and she hates him. Sarah goes home, and Henry asks if she went to Maurice’s house. She asks Henry if he prays. He says he does in church. She asks what he believes in. He says he believes in doing one’s best. She cries, and he says he will take her to the country with him.
On the street Sarah hears Smythe (Michael Goodliffe) giving a speech challenging religious beliefs so that they could improve the world. Sarah meets with Smythe, who asks if she started thinking for herself. He asks why her promise is binding. She says it was a prayer, and it was answered. He mocks the idea and has a large birthmark on his face. She asks him to convince her.
Sarah narrates what she experienced when the war ended, seeing the royal family. Henry says they can sleep at night now. He says he gained an award and may be made a knight. He asks her what is wrong, but she does not say.
In church Sarah tells the priest she kept her promise, but she is not happy about it. He says she has started a long journey. She says she does not want God. She lights a candle and leaves. She walks and thinks about it and begins to feel some happiness. At home she sees Maurice and walks upstairs. She says to God that it is not fair. She writes a letter to Maurice and then rips it up.
Sarah calls on Smythe to say goodbye. She says she is going back to Maurice. She says she taught him to find God by his hate. He says she is breaking her promise as he advised but on irrational grounds. He does not believe in God because of his scarred face. She says goodbye.
At home Henry says he talked with Maurice, and he has a bad headache. He says he loves her even though they no longer do anything together. He says he cannot do without her. He knows she cannot have a child, but she just learned that he knew. She promises she will not leave him.
Sarah believes she closed the door on Maurice, who is reading her journal. He calls her, but she says she has a bad cold and won’t see him. She asks him to promise not to come. He hurries in the rain. Sarah walks in the rain and gets on a bus. Maurice sees her and takes a taxi. At the church door she asks him to leave her alone. He says it was his fault. He advises her to take care of herself. He will wait until things are straight with Henry. She says it is too late. She says Henry is more jealous than he. She asks him not to drive her away from there, but he calls it a prison. She says she invented a God. He says he loves her, and they will be happy. They are going away together. She says she was not running away from him. She asks him to let her stay there. He urges her to get well and leaves. She goes in the church and prays.
Maurice talks to Miss Palmer in the country, and he says he will bring Sarah there to get well. He asks a taxi to wait and goes upstairs to see Henry; but he meets Sarah’s mother, Mrs. Bertram (Nora Swinburne). The doctor says he could have been called in sooner. Mrs. Bertram says Henry called in a specialist and has given Sarah everything. Mrs. Bertram tells Maurice that she was a Catholic, and her husband was unfaithful. She says she baptized Sarah. The doctor comes down and says the life just ran out. Henry says that she called, “Father, Father,” but he says she never knew her father.
Maurice goes home and opens a letter from Sarah, writing she will not go away with him even though she loves him. She writes that you must pray with all you have and that his effect on her was on the side of God. Maurice says that he believes God exists and that she lives.
This realistic drama explores the dilemma of an adulterous affair that is more loving than the marriage but is not able to replace it. The experience of love opens up the woman to a religious view of life, and she discovers that her life has been changed by the latter.