Scientist Rob Nelson investigates the strangest underground locations in the world, using the latest technology and research to shed new light on the secrets that lie just beneath our feet.

Part tech, part mystery, and part science, this show is What on Earth? meets Mysteries at the Museum -- and it's all underground. Using LIDAR, ground-penetrating radar, and all types of 3D imaging, we tell the stories of some of the strangest subterranean locations in the country. From intricate (and forgotten) sewers, caves, chemical labs, and dark matter detectors, to lost civilizations, these images look at all things covert, hidden, and unfamiliar.