
When, in her twenties, Franny begins an affair with the legendary author Leon Posen and tells him about her family, the story of her siblings is no longer hers to control.

Spending summers together in Virginia, the Keating and Cousins children forge a lasting bond that is based on a shared disillusionment with their parents and the strange and genuine affection that grows up between them. Spanning five decades, Commonwealth explores how this chance encounter reverberates through the lives of the four parents and six children involved. Before evening falls, he has kissed Franny’s mother, Beverly-thus setting in motion the dissolution of their marriages and the joining of two families. One Sunday afternoon in Southern California, Bert Cousins shows up at Franny Keating’s christening party uninvited.

The enthralling story of how an unexpected romantic encounter irrevocably changes two families’ lives.
