Back at the cottage on the family's last day, Rocky feels overwhelmed by a flood of contradictory emotions—sadness, gratitude, love, fury, awe—and concludes at fifty-four that life is simply everything, all the time. When she proposes making egg salad to use up nine eggs, the family gently rejects the idea and opts to pick up sandwiches from the deli instead. Rocky pretends offense, throws the eggs out for a laugh, then retrieves them, and embraces the change.

Driving to get sandwiches, Willa muses about Eleanor Rigby and asks Maya what happens to a caterpillar's brain during metamorphosis. Maya explains that brain tissue gets broken down and rebuilt, prompting Rocky to reflect on her own children's transformation from kids into brilliant young adults flying away.

Rocky reflects on the pain of the kids leaving home: stalking their digital traces through Amazon orders and Instagram tags, commiserating with other anxious parents on Facebook, and the bleak reality of empty-nesting with Nick. She compares parenting to hosting a decades-long dinner party the kids finally left, and likens her unrecoverable losses—miscarriages, outgrown children, missing teenagers—to a shipwreck on the pitch-black ocean floor. Maya confirms the abyssopelagic zone is indeed pitch-black.

At the beach, Jamie and Maya walk the shoreline together while Willa suns herself. Nick invites Rocky to swim. She hesitates at the waterline, puts a pebble in her mouth to taste its saltiness, then runs into the waves with Nick close behind, who catches her before she goes too deep.