The working village in Siberia. Teacher Nadezhda Sergeevna Drozdova, Nadia, a tall, young, beautiful woman with constant sadness in her gray eyes, hears from her husband about some half-crazy Lopatkin. This eccentric, you see, invented a machine for casting iron pipes and is trying to introduce it into production, not realizing that the time of single geniuses has passed. Nadia listens to her husband with confidence - Leonid Ivanovich Drozdov is the director of the plant, he is much older and more experienced than his wife. But soon, seeing her student off, Nadya finds herself in the dug-out house of a simple worker Pyotr Syanov, and here he unexpectedly meets Dmitry Alekseevich Lopatkin, a tall, thin man with a military dress and gray eyes of the sufferer. He lives in a tiny room with no windows, spending days and nights at the drawing board. Lopatkin tells her how he was born to him, a graduate of the Faculty of Physics and Mathematics, a former front-line soldier, then a teacher, the idea of ​​a machine. And the car was a success. The project was approved in Moscow and invited Lopatkin for development. Having quit his job, he arrived in the capital, but two months later he heard from ministerial officials: there is no money for development. But Lopatkin knows that this is not true - the project was cut off by Moscow professor Avdiev, who is trying to introduce his own car. Lopatkin did not lose heart, he continues to work and fight - he writes complaints to different authorities ... Nadia understands that she is not a madman, but a real hero.

Soon, Lopatkin’s efforts are bearing fruit - after a second review of the issue, the ministry made a positive decision. And Lopatkin goes to the regional city, where his design will be finalized in the design bureau. At the same time, Drozdov, having received a post in the ministry, moved with his wife to Moscow.

At the design bureau, Lopatkin collaborates with design engineers Uryupin and Maksyutenko, but soon discovers that the designers are trying to design their own car using his ideas. Lopatkin breaks their plans. Before leaving for Moscow, he receives a letter from Nadi, from which he learns that Avdiev’s model was made at the factory. Lopatkin understands that the struggle is not easy. Indeed, at a meeting of the technical council at the Giprolito Central Institute, his project was miserably failed by Avdiev’s minions, Fundator and Tepikin. Lopatkin with his usual hand writes a complaint to the ministry. Useless. The complaint falls to his enemies: Drozdov and Deputy Minister Shutikov. And again Lopatkin begins his struggle - he writes letters and complaints. Lopatkin accidentally meets a gray-haired, exhausted old man - the ingenious, but equally unrecognized and persecuted inventor, Professor Busko. Busko offers shelter and help. Two inventors begin to lead the ascetic life of single heroes. They get up strictly according to the regime, have breakfast with tea with brown bread and get to work. At exactly twelve, Lopatkin leaves the house and walks his daily eight-kilometer route, reflecting and breathing fresh air. At exactly three, he is already at home, and they are waiting for their joint dinner - a pot of cooked potatoes and pickles. Sometimes a doorbell rings and neighbors in a communal apartment pass a package from some high authority with another refusal. Looking casually at the paper, the inventors continue their work. They earn money by unloading cars and spend it extremely economically. But one day the postman handed them a bag with a dense bundle of scribbles and a note without a signature: "Use your money, at your discretion." Now, when the mysterious well-wisher gave them the opportunity to work without being distracted by everyday life, Lopatkin heard an inner voice reminding him that he needed to live.

He began to go to the theater and conservatory. The music of Chopin, and then Bach helped him formulate important life attitudes: a person is not born for fatty foods and well-being, this is the joy of worms. Man must be a comet and shine. “Here is my clue!” Once at the conservatory Lopatkin saw a young, beautiful, chubby girl with a suede mole and recognized Nadia in her. Their eyes met, and Dmitry Alekseevich felt a pleasant gasp. From a conversation with Nadia, he learned that she had nothing in common with her husband, Lopatkin’s heroism admired her, she was a donor of money and was ready to help further. For her, a permanent business was found - to write on a typewriter and send statements and complaints of inventors to several instances at once ... And finally, the months-long work was completed - a new version of the machine was ready, and Lopatkin decided that it was time to reappear on the surface. A familiar secretary arranges for him to meet with the minister. And he, after listening to Lopatkin, ordered to send the project to recall Avdiev’s scientific enemy. At a new meeting of the technical council, Lopatkin’s project was a great success. Work on preparation for implementation has begun to boil. And it was at that moment that pipes cast by Avdiev’s machine were brought from the factory. Work stops. But long-time well-wisher Lopatkina, Ph.D. and plant director Galitsky, comes to the rescue. Lopatkin is invited to talk to a certain institute, whose director in general form offers work on a secret order. Lopatkin can use his new invention, made in collaboration with Nadia. He continues to work in Giprolit, but in a closed laboratory. And again, at the final stage of the work, the sinister figures of Avdiev and Uryupin appear. A denunciation is written in which Lopatkin is accused of criminal negligence: he allowed an outsider, Drozdov, to secret documentation. Lopatkina is tried, sentence: eight years in prison. Decided to destroy the laboratory papers. But an honest engineer Antonovich saves some of the documents. Thanks to these documents, the case is being reviewed and Lopatkina ahead of schedule, after a year and a half, is released. Lopatkin is back in Moscow and learns that at the request of Galitsky, engineers working under the direction of Lopatkin recreated the destroyed drawings and the machine has already been built, it successfully produces products. Avdiev, Shutikov, Uryupin and others, intoxicated by their victory, still do not know anything. They have other concerns: serious shortcomings of the machine manufactured under the leadership of Avdiev were discovered, it was overusing metal. And this cost overrun caused considerable damage to the country. Uryupin offers Shutikov to petition for a change in metal consumption standards, that is, to legalize marriage. At that moment, it became known that there was an economical Lopatkin machine. The offended inventor had the opportunity not only to prove his innocence, but also to accuse Shutikov, Drozdov and others of knowingly wrecking. Drozdov and the company decide to seize the initiative. There is an order for the ministry, in which the blame for what happened was blamed on Uryupin and Maksyutenko, who even tried to hide the marriage and criminal unprofitability of their car through a change in standards. Fundator and Tepikin are also held accountable. Lopatkin’s victory is complete. The Minister gives him the opportunity to work at Giprolit and guarantees support.

At a gala banquet at the institute, Lopatkin meets his completely unconquered enemies, Avdiev, Shutikov, Fundator, Tepikin, and hears from them an offer to drink the world. “No,” he replies with fighting enthusiasm. “We will still fight with you!” Lopatkin and Nadia went to the balcony, covered in snow. "What are you thinking about? - asked Nadia. “About a lot,” replied Dmitry Alekseevich, with an inner eye seeing the endless road in the dark, which attracted with its mysterious bends and severe responsibility. "If I tell you:" Let's move on ... "?"

Nadia did not answer. Just got closer ...