It is the summer of 1992 and a gypsy moth invasion blankets Avalon Island. Ravenous caterpillars disrupt early summer serenity on Avalon, an islet off the coast of Long Island, dropping onto novels left open on picnic blankets, crawling across the T-shirts of children playing games of tag and capture the flag in the island's leafy woods. The caterpillars become a relentless topic of island conversation and the inescapable soundtrack of the season.
It is also the summer Leslie Day Marshall, the only daughter of Avalon's most prominent family, returns with her husband, a botanist, and their children to live in The Castle, the island's grandest estate. Leslie's husband Jules is African-American, and their children bi-racial, and islanders from both sides of the tracks form fast and dangerous opinions about the new arrivals.