From Genesis and the Book of Enoch to Greek mythology and the hybrid gods of Egypt and Mesopotamia, ancient cultures repeatedly described a forgotten age when powerful nonhuman beings interacted with mankind and produced extraordinary offspring. Were these simply symbolic myths created independently around the world—or distorted memories of real beings once known as the Nephilim? Could the strange giant traditions, elongated skulls, hybrid deities and mysterious megalithic structures preserve fragments of knowledge passed down from a civilization that disappeared before recorded history?