Some mysteries from ancient times have yet to be solved, such as how the ancient Egyptians constructed the Great Pyramid with such mathematical accuracy. Other enigmas are much more recent, such as twentieth-century UFO sightings and alleged alien abductions, as well as the possible existence of top-secret government files relating to these events. Some think that these strange phenomena have been covered up by a government conspiracy. This set explores how and why these beliefs may have come about. Features include: Interviews, quotations, and testimonies are presented in an engaging narrative that allows students to describe the relationship between a series of events or concepts. Documentation that includes photographs and reports to help students locate information relevant to a given topic efficiently.