The central conflict arises from the gradual erosion of the Buddenbrook family's commercial dominance as their traditional values clash with the shifting economic and psychological realities of the modern era. The narrative follows four generations of a wealthy Lübeck merchant family, focusing on the tension between the rigid expectations of bourgeois success and the emerging artistic or individualistic temperaments of the descendants. Thomas Buddenbrook serves as the primary lens, struggling to maintain the family firm while his own internal decline mirrors the external decay of his social class. The novel utilizes a multi-generational structure to examine how the accumulation of wealth and status eventually gives way to spiritual and physical exhaustion.

Readers and critics frequently highlight the novel's meticulous attention to detail and its profound psychological depth. Discussion often centers on the masterful way Mann portrays the inevitability of decline, treating the family's fall as both a social and a personal tragedy. Many observers note that the pacing is deliberate, allowing the reader to fully inhabit the changing world of the characters over several decades. The balance between the external business environment and the internal lives of the family members is widely considered a hallmark of the work's enduring impact. Scholars often point to the autobiographical elements as a key factor in the authenticity of the setting and the emotional resonance of the characters' struggles.