*Attentive young Lynn relishes the "dark crystal waters" of the swimming hole and treasures of "the light-dappled forest" of Elkmont in the Great Smoky Mountains. She spends summers exploring the woods from a family cabin there, though the Park Service is now displacing park residents. Curiosity about a striking synchronous firefly phenomenon--a hypnotizing six-second "spangled beat" that has mesmerized her her whole life--leads self-taught naturalist Lynn Frierson Faust down a long and rewarding research path that eventually proves these special lightning bugs' (Photinus carolinus) existence to the scientific community and invites the world to appreciate their wonder. Immersive watercolor-and-digital paintings create a world readers will long to get lost within, with moss clinging to hulking boulders and the shimmer of countless fireflies lighting up the darkening sky. A notable variety in perspectives and page layouts includes panels and lush full-page spreads, while a brilliantly designed rendering of the "exquisite unity of the light show fireflies" interspersed with swaths of darkness is a visual showstopper. Evocative language keeps pace, pairing admiring details about Lynn's patient work with pleasingly detailed descriptors of her environs: "Light cascades down the hillside, like a glittering, star-filled waterfall." Rich back matter demonstrates thorough research and supports young naturalists' continued curiosity. An absolute must-purchase--truly enlightening and positively radiant.