Beginning in 1875, the Buddenbrook family enjoys a period of prosperity, maintaining their esteemed reputation and financial success. Johann Buddenbrook, having inherited wealth and business acumen from his father, continues to uphold the family's stature. Upon his passing, the family business is entrusted to his eldest son, Jean, while his daughter, Antonie (known as Tony), is raised with a sense of aristocratic duty, embodying the family's noble aspirations.

Tony's Marital Trials

Tony blossoms into a striking young woman, but her life takes a turn when Herr Grünlich, a suitor whose financial intentions are questionable, shows interest in her. Despite her disdain for Grünlich's servility, Tony's parents push for the match, prioritizing stability over her personal feelings. Grünlich's proposal comes with the promise of a generous dowry, which temporarily stabilizes his faltering finances. Tony, adhering to family expectations, marries him and moves to the countryside, although she is unhappy with her isolation from friends and family.

Christian's Struggles and Business Challenges

Meanwhile, Tom, Jean's other son, becomes a pivotal figure in the business, demonstrating a keen interest in its operations. Christian, Tom’s brother, is less inclined toward such responsibilities, choosing instead to seek opportunities abroad due to his persistent health issues. Eventually, Jean realizes Grünlich's ulterior motive—marrying Tony to bolster his failing credit—and supports her return home after Grünlich's financial situation deteriorates. A divorce is swiftly arranged, freeing Tony from Grünlich's deceit, and she finds solace in her family's support.

Family Dynamics and New Beginnings

Jean's devotion to family tradition remains unwavering, and Tony finds comfort and happiness back at home, channeling her energies into supporting her brother Tom and the family business. Although Christian struggles to find his footing in South America, upon his return, he is given a nominal role in the firm that he is disinclined to fulfill. Following Jean's death, Tom assumes leadership of the business, a responsibility he approaches with earnest dedication, though he feels the weight of his father's legacy.

New Marriages and Continuing Drama

Tom's marriage to Gerda, a musician with a substantial dowry, brings new life to the Buddenbrook mansion. Tony, seeking another chance at happiness, weds Permaneder, a beer merchant. However, her second marriage soon falters due to his infidelity, and she returns home, disheartened but determined. Tony is taken aback when Permaneder offers no resistance to the divorce and amicably returns her dowry.

Legacy and Family Tensions

Tom and Gerda welcome a son, Hanno, who inherits his mother's artistic inclinations but also a frail constitution. Despite Tom's efforts to inculcate a passion for the family business in his son, Hanno remains indifferent. The death of Frau Buddenbrook brings about disputes over inheritance, with Christian demanding his share and clashing with Tom, who is tasked with maintaining the estate.

Decline and Tragedy

Despite Tom's diligent stewardship, the Buddenbrook business begins to falter under external economic pressures. Christian, unable to adapt to the family's expectations, moves to Munich, where he becomes entangled with a less reputable crowd. Tom's health deteriorates, and he fears that Christian, who shirks responsibility, might outlive him. Meanwhile, Tony orchestrates a marriage for her daughter Erica, but this too ends in scandal when Erica's husband is imprisoned for unethical dealings.

The End of an Era

Tragedy befalls the Buddenbrooks when Tom dies suddenly after collapsing in the snow. His death is a profound loss, particularly for Tony, who feels the absence of a familial anchor. Christian, preoccupied with his own troubles, shows little sorrow, while Gerda mourns the loss of a loving partner. After the funeral, Christian returns to Munich, marries his longstanding partner, and soon finds himself institutionalized due to his deteriorating mental health.

Hanno's Fragile Existence

Life at the Buddenbrook residence continues, but young Hanno struggles with his health and ultimately succumbs to a typhoid epidemic at the age of fifteen. With his passing, the lineage of the Buddenbrook family comes to an end, marking the conclusion of a once-thriving dynasty that could not withstand the trials of time.