The book "Commonwealth" by Ann Patchett follows the lives of two families, the Cousins and the Keatings, whose lives intertwine over several decades. The story unfolds from a chance encounter at a christening party, which sets off a series of events that impact both families in profound ways. The emotional and relational dynamics explore themes of love, loss, and the consequences of choices made over time.
As the narrative shifts between different time periods and perspectives, readers witness the growing complexities of family relationships and how secrets and betrayals shape their lives. The characters, particularly the children from both families, navigate challenges that stem from their blended backgrounds, revealing the intricacies of familial bonds.