As the full moon crests the horizon, ruby orbs of light begin to rise out of the Mekong River. As if by magic, they float silently into the air and then evaporate in the inky blackness, A phenomenon that awes and delights observers privileged to have seen them. For centuries, their existence was a closely-held secret among villagers living near the northeastern town of Nong Khai. Then, the miraculous event was discovered by outsiders who now flock to the riverbanks each October full moon night.