From Scotland's Loch Ness to Vermont's Lake Champlain, witnesses tell terrifying tales of prehistoric, long-necked creatures that inhabit the waters.

This episode features large images that are visible only from the air, like crop circles, Stonehenge, and the Nazca Lines.

This episode features research on Bigfoot in Northern California, Texas, and Florida, where it's known as Skunk Ape.

The Loch Ness Monster, The Lake Champlain Monster, Bigfoot, Mothman, and the Jersey Devil are all investigated, including the Men in Black's involvement with Mothman.

This episode features the mysteries of Machu Picchu, Peru and Sedona, Arizona.

This episode features people who witnessed alien encounters around the world.

From the magnificent carved symbols of Scotland's Rosslyn Chapel to mysterious codes hidden in books and monuments across England, we’ll track down secret clues to find out what the Holy Grail actually is and where it might be concealed.