Throughout the world, ancient objects have been found that leave archaeologists at a loss. Could these impossible artifacts suggest that advanced–and perhaps even extraterrestrial–civilizations existed on Earth thousands of years before our own?

In the 20th century, pioneering scientists, journalists and investigators defied convention and began documenting UFOs. Now, with incredible new UFO accounts coming to light, will their work finally culminate in undeniable proof of extraterrestrial visitation?