Charles, a shy and serious young man, moves to Paris to study law. He stays with his cousin Paul, a charming and hedonistic student who effortlessly balances his studies and social life. Paul's circle of friends is frivolous and decadent, indulging in late-night parties and casual romances. Despite his cousin's influence, Charles focuses on his studies but finds himself increasingly drawn to Paul's carefree lifestyle and the circle of friends that come with it. One of Paul's friends, Florence, catches Charles's eye, and he becomes infatuated with her. Florence, however, is more interested in Paul, leading to a complicated triangle of affection and rivalry.

As Charles tries to navigate this new world of temptation, his academic focus begins to slip, causing tension between his aspirations and his budding feelings for Florence. Paul, meanwhile, continues his carefree existence, seemingly indifferent to the turmoil he has inadvertently caused. The contrast between the cousins' personalities and life choices grows more pronounced as the end of the term approaches, causing both to confront the consequences of their actions and desires. The story explores themes of ambition, morality, and the impact of one's environment on personal growth, leading to a poignant resolution that underscores the inherent differences between the two cousins.