"Riddles in the Sand" they are the famous Nazca lines and giant ground drawings etched across 30 miles of gravel-covered desert near Peru's southern coast. Not only do these images appear here, but they are also discovered in the Desert of California. Who or what drew these images, and why? Robyn and EW find themselves deep in the desert heat and try to cool off this subject of unknown portions. Join us as they feel the heat of Desert Giants.