All it takes is one: one coral gamete to start a colony, one person to make a difference, one idea to change the world. The ongoing efforts to save and rebuild the world's coral reefs—with hammer and glue, and grafts of newly grown coral—are the living legacy of Ken Nedimyer, founder of the Coral Restoration Foundation. Kate Messner and Matthew Forsythe tell the true story of the coral restoration pioneer in this brilliant tribute to the wonders of nature and the power of human hope.