John Beaver is a young man of twenty-five years. He lives in London in a house of his mother, who is engaged in renting apartments. After graduating Oxford, until the crisis began, John worked in an advertising agency. Since then nobody has been able to find him a place. He gets up late almost every day, sits by the phone in anticipation that someone will call him to ask to dinner. Often at the last minute it happens. In the coming weekend he is going to stay in Hetton Abbey with his recent acquaintance Tony Last.
After receiving a telegram from Beaver, Tony, who wanted to spend a quiet holiday with his family, his wife Brenda, and son John Andrew, he does not express special delight on his arrival and entrusts his wife to entertain the guest. Beaver makes a good impression on Brenda and eventually she even begins to like him a lot. Branda wants to find a flat in London and Beaver’s mother helps her. Soon Tony's wife begins to realize that she got fascinated by her husband’s friend. Arriving to London she and her sister Marjorie go to the restaurant of one of their common friend where she meets Mrs. Beaver and Lady Kokpers; the last invites them all to her party in few days. When the time comes for Brenda to leave London Beaver accompanies her to the station, but at her request to accompany her to Polly Kokpers’s party he replies with a clumsy excuse, because, in his mind's calculations, it would cost him a few pounds since before the reception he will have to take Brenda to the restaurant. Brenda is upset.
The next day there comes a telegram from Beaver in which he reports that he was able to settle his business and is willing to accompany her to the party. Branda cheers up. Brenda pays for the lunch in the restaurant, despite Beaver’s protests. On the way to Polly, sitting in the backseat of a taxi, Brenda pulls John to herself and kisses him. The next day after the party the entire London talks only about one thing - that Brenda and Beaver begin an affair.
For three days Brenda returns to Hetton, to her husband and son, and then again, under the pretext of the hassle about the apartment, leaves for London. She phones Tony in the morning and evening and spends most of her time with Beaver. Soon she tells her husband that she wants to go to the women's courses in economics at the university so she will have to spend more time in London.
One day Tony without a notice comes to London. Brenda is dissatisfied with his unexpected arrival and, referring to being busy, refused to meet with him. Tony goes to the club where together with his friend Jock Grant-Menzies gets heavily drunk and the whole evening phones Brenda, it makes her very angry. Back in Hetton Tony quarreles with his son who, missing his mother, throws questions to his tired and irritable father.
Following these events two weekends in a row Brenda arrives to Hetton with her friends. Guilt gnaws her and she wants her husband to experience a love affair. She wants him to become interested in her new friend Jenny Abdul Akbar, who once was married to a black man. She is a very eccentric but nice lady. Tony however finds her tedious.
One day when Brenda as usual is away, hunting collection is arranged in the Hetton forest. John Andrew, who already know how to ride a pony, is allowed to be present. After the start of hunting the boy under the supervision of groom Ben is sent home. On the way back an accident happens with the child: Miss Ripon’s wayward horse gets scared, stands on its hind legs and strikes John’s with its hoof. The boy falls into a ditch. Death occurs instantly. Mourning envelops the house. Jock Grant-Menzies, who was present at the hunt, goes to London to inform Branda about the incident. Brenda at this time is at a party. Learning of the death of her son she weeps bitterly. After the funeral she quickly leaves Hetton and from London writes Tony a letter in which reports that will not return home, that she is in love with Beaver and wants a divorce.
For registration of divorce it is necessary for Tony to have witnesses who observed his affair with some other woman. For this he findss in a bar some Millie, a girl of easy virtue, and goes with her to Brighton. The detectives follow them. Millie without telling Tony takes with her her daughter, who constantly revolves around adult and pesters Tony with her requests and whims.
On his return to London Tony has a serious conversation with Branda’s elder brother Reggie, who requires for Branda alimony amount twice the one that Tony is able to give. In addition there come up some unpleasant facts so in the end Tony refuses to give Brenda a divorce. To require it she cannot, because the testimony of witnesses in Brighton do not cost a penny, because in the room there was a child all the time and the girl both nights slept in the room that was supposed to be taken by Tony. Instead of divorce Tony decides to leave for a while and goes on an expedition to Brazil in search of a Lost Castle.
In the journey Tony is accompanied by Dr. Messinger, an experienced researcher, though still quite a young man. During the voyage to the shores of South America Tony meets a girl named Teresa de Vitre, who after two years of study in Paris is returning home to Trinidad. Between them there appears a fleeting affair, but as soon as she learns that Tony is married she loses any interest in him. After landing in Brazil Tony and Dr. Messinger come into contact with the local Indians, and for some time live near their settlements terribly suffering from bothersome insects, but hoping that Indians will help them to get to the tribes that have some guidelines on how to find the Lost Castle.
The Indians are building boats for travel on the river, deliver them to the land border of payvajs tribes and disappear at night. Further the doctor and Tony are moving downstream on their own. On the way Tony gets ill and has high fever. Many days and nights he spends in an unconscious state. Dr. Messinger starts to move alone to bring someone to help Tony. The doctor drowns in the maelstrom and Tony barely makes his way through the jungle and forest and gets to the Indian village. There he meets with old Mr. Todd, who cannot read but enjoys listening when someone reads a book, a considerable number of which was left him by his father, who once worked there as a missionary. He cures Tony but does not allow him to leave forcing Tony constantly read and reread all the books aloud. Tony almost a year lives in his hut. Once Mr. Todd makes him sleep for two days, and when Tony wakes up tells him that some Europeans were looking for Tony and he gave them his watch and assured that Tony died. Now no one will ever be looking for him and Tony will have to spend all his life in the Indian village.
Brenda learning that she became a widow marries Jock Grant-Menzies, but Hetton Abbey on Tony’s bequest is left to some of his relatives.