It's March 1980, and Carol Girard and her husband are living an ordinary life in a small town in the Adirondacks. They have just had their first child, and though Carol is struggling with the challenges of new motherhood, her future seems clear. Until something extraordinary happens: an inexplicable flickering of light in the sky, which is ultimately determined to be communication from intelligent life on another planet. But these beings are eleven light-years away, and nothing is known about them other than the fact that they seem to know we exist too. And so begins a decades-long exchange of messages with this mysterious, faraway civilization. As humanity reels from a shifting understanding of its place in the universe, we follow the stories of the Girard family: Carol, whose fascination with this other life sparks a desperate search for spiritual meaning; Michael, her loyal son, who finds solace not in the stars above his head but in the ground beneath his feet; and Ro, Carol's bright and ambitious daughter, whose childhood goal to work in interstellar communication will evolve into something far grander. Tracing five decades of love, loss, ambition, and self-discovery, The Radiant Dark is a stunning examination of a family navigating their lives with the knowledge that we are not alone.