At the beginning of the story, the protagonist, a wealthy banker named A.G.P., holds to the former view. He believes that there is no greater joy than in experiencing all that life has to offer, including food, drink, music, and women. He is so sure that this is the best way to live that he makes a bet with his friend, a young lawyer named Ivan Ivanovich, that he can remain in solitary confinement for 15 years without going insane.
Ivan Ivanovich, on the other hand, believes that the truly fulfilling life is one that is devoted to the pursuit of knowledge and intellectual growth. He argues that material pleasures are fleeting and insubstantial, and that only by cultivating the mind and soul can a person truly find happiness and contentment.
The bet is set, and A.G.P. moves into a small room in Ivan Ivanovich's house, where he is to remain for the next 15 years. During that time, he is allowed no contact with the outside world, except for the daily delivery of food and newspapers.
At first, A.G.P. finds it difficult to adjust to his new life. He misses the luxuries he was accustomed to, and he struggles with loneliness and boredom. But as time goes on, he begins to discover the joys of simple living. He finds pleasure in reading and studying, and he begins to appreciate the beauty of nature and the company of his fellow man.
After 15 years, the bet is up, and Ivan Ivanovich comes to collect A.G.P. from his room. He is amazed to find that his former friend is in good health and spirits, and he seems to have been transformed by his experience.
A.G.P. tells Ivan Ivanovich that he has learned a great deal during his confinement, and that he now believes that the pursuit of knowledge is far more rewarding than the pursuit of pleasure. He says that he is grateful to Ivan Ivanovich for giving him the opportunity to learn this lesson.
The story ends with A.G.P. leaving Ivan Ivanovich's house and walking out into the bustling city, where he is ready to begin a new life.