In the affluent beachfront community of Monterey, Cal., a suspicious death at a coastal elementary school fundraiser draws attention to the frictions among some of the mothers. Madeline (Reese Witherspoon) and Celeste (Nicole Kidman), longtime friends and confidantes, welcome newcomer Jane (Shailene Woodley) and her son, Ziggy (Iain Armitage), into their inner circle, much to the chagrin of another mother, Renata (Laura Dern). An incident with the children at school causes battle lines to be drawn.