Set in the present day in the rural community of Feathertown, Tennessee, this novel tells the story of Dellarobia Turnbow, a petite, razor-sharp 29-year-old who nurtured worldly ambitions before becoming pregnant and marrying at seventeen. Now, after more than a decade of tending to small children on a failing farm, oppressed by poverty, isolation and her husband's antagonistic family, she has mitigated her boredom by surrendering to an obsessive flirtation with a handsome younger man. In the opening scene, Dellarobia is headed for a secluded mountain cabin to meet this man and initiate what she expects will be a self-destructive affair. But the tryst never happens. Instead, she walks into something on the mountainside she cannot explain or understand: a forested valley filled with a lake of silent red fire that appears to her a miracle. In reality, the forest is ablaze with millions of butterflies. Their usual migratory route has been disrupted, and what looks to be a stunningly beautiful view is really an ominous sign, for the Appalachian winter could prove to be the demise of the species. Her discovery of this phenomenon ignites a media and religious firestorm that changes her life forever. After years lived entirely in the confines of one small house, Dellarobia finds her path suddenly opening out, chapter by chapter, into blunt and confrontational engagement with her family, her church, her town, her continent, and finally the world at large.