The novel is written in the second person singular: the author, as it were, identifies the hero and the reader: "You put your left foot on a copper bar and try in vain to push the sliding compartment door with your right shoulder ..."

Leon Delmont, director of the Paris branch of the Italian company Scabelli, which produces typewriters, secretly from his colleagues and from his family, he leaves for Rome for a few days. On Friday at eight in the morning, having bought a novel at the station to read on the road, he gets on the train and starts his journey. He is not used to riding the morning train - when he travels on business for the company, he travels in the evening, and not third class, as it is now, but first. But the unusual weakness is explained, in his opinion, not only by the early hour - this age makes itself felt, because Leon is already forty-five. But, leaving his aging wife in Paris, Leon goes to Rome to his thirty-year-old mistress, next to whom he hopes to find the outgoing youth. He notes with a glance all the details of the landscape changing outside the window, with an attentive glance glances over his fellow travelers. He recalls how his wife Anrietta got up early in the morning to serve him breakfast - not because she loves him so much, but in order to prove to him and to himself that he cannot do without her even in small things - and he reflects whether she had gone far in her conjectures as to the true purpose of his current trip to Rome. Leon knows the whole route by heart, because he regularly travels to Rome on business, and now he mentally repeats the names of all stations. When a young couple sitting in the same compartment with him (Leon assumes that these are newlyweds making almost their first trip together) goes to the dining car, Leon decides to follow their example: although he recently drank coffee, visiting the dining car is for him an indispensable part of the journey, is included in his program. Returning from the restaurant, he discovers that his favorite place, in which he used to sit and before that he sat, is occupied. Leon is annoyed that he did not guess, leaving, to put the book as a sign that he will be back soon. He asks himself why, on the journey that should bring him freedom and youth, he feels neither excitement nor happiness. Is it really that he left Paris not in the evening, as he was accustomed to, but in the morning? Has he become such a routine, a slave to habit?

The decision to go to Rome came suddenly. On Monday, returning from Rome, where he was on a business trip, Leon did not think that he would go there again so soon. He had long wanted to find a job in Paris for his mistress Cecile, but until recently he had not taken any serious steps in this direction. However, on Tuesday he called one of his clients - the director of a travel agency Jean Durier - and asked if he knew about any suitable place for Leon's acquaintance, a thirty-year-old woman of extraordinary abilities. Now this lady serves as secretary to the military attaché at the French embassy in Rome, but she is ready to agree to a modest salary, just to return to Paris again. Durier called the same evening and said that he planned to reorganize his agency and was ready to provide a job for Leon's acquaintance on very favorable terms. Leon took the liberty of assuring Durier of Cecile's agreement. At first Leon thought of simply writing Cecile, but on Wednesday, November thirteenth, the day Leon was forty-five years old and the festive dinner and congratulations from his wife and four children annoyed him, he decided to put an end to this long-running farce, this long-standing falsehood. He warned his subordinates that he would leave for a few days, and decided to go to Rome to personally inform Cecile that he had found her a place in Paris and that, as soon as she moved to Paris, they would live together. Leon is not going to arrange a scandal or divorce, he will visit the children once a week and is sure that Henrietta will accept his terms. Leon looks forward to how Cecile will be delighted with his unexpected arrival - to surprise her, he did not warn her - and how she will be even more delighted when she learns that from now on they will not have to meet occasionally and stealthily, and they can live together and not part. Leon thinks over to the smallest detail how on Saturday morning he will be waiting for her on the corner opposite her house and how surprised she will be when she leaves the house and suddenly sees him.

The train stops, and Leon decides, following the example of his English neighbor, to go to the platform to get some air. When the train starts to move, Leon again manages to get into his favorite seat - the man who took it while Leon was going to the dining car, met an acquaintance and moved to another compartment. Opposite Leon sits a man reading a book and making notes in its margins, probably he is a teacher and is going to Dijon to give a lecture, most likely on legal issues. Looking at him, Leon tries to imagine how he lives, what kind of children he has, compares his lifestyle with his own and comes to the conclusion that he, Leon, despite his material well-being, would be more worthy of pity than a teacher studying favorite thing, if not for Cecile, with whom he will start a new life. Before Leon met Cecile, he did not feel such a strong love for Rome, only discovering it for himself with her, he was imbued with a great love for this city. Cecile for him is the embodiment of Rome, and, dreaming of Cecile beside Henriette, in the very heart of Paris he dreams of Rome. On Monday, returning from Rome, Leon began to imagine himself as a tourist who visits Paris once every two months, at most once a month. To prolong the feeling that his journey is not over yet, Leon did not dine at home and came home only in the evening. A little over two years ago, in August, Leon went to Rome. Opposite him in the compartment was Cecile, whom he had not yet met. He first saw Cecile in the dining car. They got into a conversation, and Cecile told him that she was Italian by her mother and was born in Milan, but was listed as a French citizen and was returning from Paris, where she had spent her vacation. Her husband, who worked as an engineer at the Fiat factory, died in a car accident two months after the wedding, and she still cannot recover from the impact. Leon wanted to continue the conversation with Cecile, and, leaving the dining car, he walked past his first-class compartment and, following Cecile, who was traveling in third class, to her compartment, remained there.

Leon's thoughts turn now to the past, then to the present, then to the future, in his memory, then old, then recent events emerge, the narrative follows random associations, repeats episodes as they appear in the hero's head - randomly, often incoherently. The hero is often repeated: this is not a story about events, but about how the hero perceives events.

It occurs to Leon that when Cecile is not in Rome, he will no longer go there on business trips with the same pleasure. And now he is going to talk to her for the last time about Rome - in Rome. From now on, of the two of them, Leon will become a Roman, and he would like Cecile, before she leaves Rome, to pass on to him most of her knowledge, until they were swallowed up by Parisian everyday life. The train stops at Dijon. Leon gets out of the train to stretch his legs. So that no one takes his place, he puts on him a book he bought at a Paris train station, which he has not yet opened. Back in the compartment, Leon recalls how a few days ago Cecile accompanied him to Paris and asked when he would return, to which he replied: "Alas, only in December." On Monday, when she again escorts him to Paris and asks again when he will return, he will again answer her: “Alas, only in December,” but not in a sad, but in a joking tone. Leon dozes off. He dreams of Cecile, but her face is frozen with the look of disbelief and reproach that so struck him as they said goodbye at the station. And is it not because of the fact that he wants to part with Henrietta, that in her every movement, in every word, there is an eternal reproach? Waking up, Leon recalls how two years ago he also woke up in a third-class compartment, and Cecile was dozing in front of him. Then he did not know her name yet, but nevertheless, taking her in a taxi to the house and saying goodbye to her, he was sure that sooner or later they would definitely meet. Indeed, a month later, he met her by chance at a cinema where a French film was shown. At that time, Leon stayed in Rome for the weekend and enjoyed seeing its sights with Cecile. So their meetings began.

Having come up with biographies for his fellow travelers (some of them managed to change), Leon begins to select names for them. Looking at the newlyweds, whom he christened Pierre and Agnes, he recalls how he once rode like this with Henriette, not suspecting that one day their union would become a burden to him. He ponders when and how to tell Anriette that he has decided to part ways with her. A year ago, Cecile came to Paris, and Leon, explaining to Henriette that he was connected with her in the service, invited her into the house. To his surprise, the women got along well, and if anyone felt uncomfortable, it was Leon himself. And now he has an explanation with his wife. Four years ago, Leon was in Rome with Henriette, the trip was unsuccessful, and Leon asks himself if he would have loved his Cecile so much if this unfortunate trip had not preceded their acquaintance.

It occurs to Leon that if Cecile moves to Paris, their relationship will change. He feels that he will lose her. Probably, he should have read the novel - after all, that's why he bought it at the station, in order to while away the time on the road and not allow doubts to settle in his soul. After all, although he never looked at the author's name or the title, he did not buy it at random, the cover indicated that he belonged to a certain series. The novel undoubtedly speaks of a man who is in trouble and wants to be saved, sets off on a journey and suddenly discovers that the road he has chosen leads not at all where he thought he was lost. He understands that, having settled in Paris, Cecile will become much further from him than when she lived in Rome, and will inevitably be disappointed. He understands that she will reproach him for the fact that his most decisive step in life turned into defeat, and that sooner or later they will part. Leon imagines that on Monday, after taking the train in Rome, he will be glad that he did not tell Cecile about the job he found for her in Paris and about the apartment offered for a while by friends. This means that he does not need to prepare for a serious conversation with Henrietta, for their life together will continue. Leon recalls how he and Cecile traveled to Rome after her unsuccessful arrival in Paris, and on the train told her that he would never leave Rome, to which Cecile replied that she would like to live with him in Paris. Views of Paris hang in her room in Rome, just as views of Rome hang in Leon’s Paris apartment, but Cecile in Paris is just as inconceivable and unnecessary for Leon as Henriette is in Rome. He realizes this and decides not to tell Cecile about the place he has found for her.

The closer Rome is, the harder Leon is in his decision. He believes that he should not mislead Cecile and, before leaving Rome, should directly tell her that, although this time he came to Rome only for her sake, this does not mean that he is ready to forever link his life with her. But Leon is afraid that his confession, on the contrary, will instill hope and confidence in her, and his sincerity will turn into a lie. He decides this time to refuse a date with Cecile, since he did not warn her about his arrival.

In half an hour the train will arrive in Rome. Leon picks up a book, which he never opened for the entire journey. And he thinks: “I have to write a book; only in this way can I fill the void that has arisen, I have no freedom of choice, the train rushes me to the final stop, I am bound hand and foot, doomed to roll on these rails. " He understands that everything will remain the same: he will continue to work for Scabelli, live with his family in Paris and meet with Cecile in Rome, Leon will not say a word to Cecile about this trip, but she will gradually understand that the path of their love does not lead anywhere. Several days, which Leon will have to spend in Rome alone, he decides to devote to the writing of the book, and on Monday evening, without seeing Cecile, he will sit on the train and return to Paris. He finally understands that in Paris Cecile would become another Henriette and in their life together the same difficulties would arise, only even more painful, since he would constantly remember that the city, which she should have brought closer to him, - long away. Leon would like to show in his book what role Rome can play in the life of a person living in Paris. Leon thinks about how to make Cecile understand and forgive him that their love turned out to be a lie. Here, only a book can help, in which Cecile will appear in all her beauty, in the halo of Roman grandeur, which she so fully embodies. The most reasonable thing is not to try to reduce the distance separating these two cities, but in addition to the real distance, there are also direct transitions and points of contact, when the hero of the book, walking not far from the Parisian Pantheon, suddenly realizes that this is one of the streets near the Roman Pantheon.

The train is approaching Termini station, Leon recalls how, immediately after the war, he and Henrietta, returning from their honeymoon trip, whispered when the train departed from Termini station: "We will be back as soon as we can." And now Leon mentally promises to Henriette to return with her to Rome, because they are not so old yet. Leon wants to write a book and revive for the reader a decisive episode in his life - a shift that took place in his mind as his body moved from one station to another past the landscapes flashing outside the window. The train arrives in Rome. Leon exits the compartment.