It’s an autumn weekend at a comfortable New York country house where two deeply intertwined families have gathered to mark the host’s 52nd birthday. Together, the group forms an enviable portrait of middle age. The wives and husbands have been friends for over 30 years, their teenage daughters have grown up together, and the dinners, games and rituals forming their days all reflect the rich bonds between them. This weekend, however, something is different. An unforeseen curdling of envy and resentment will erupt in an unspeakable act, the aftermath of which exposes treacherous fault lines upon which they have long dwelt.