An exploration of the world's most fascinating, strange and inexplicable mysteries. Compelling contributions from scientists, historians, and witnesses as they seek to shed light on how the impossible can happen.
Humanity has launched satellites into outer space and submarines to the ocean floor - but the ground below Earth's surface remains a mystery. (S3, ep 40)
Explore whether time travel has already occurred - deliberately or by accident - and meet the scientists who believe it is theoretically possible. (S4, ep 1)
Age-old ruins can stand with their true history seemingly erased by time - can modern research discover why these ancient structures were built? (S4, ep 2)
The Vikings were infamous for being bloodthirsty, seafaring warriors - but historians are learning surprising new things about this Norse society. (S4, ep 3)
Join William Shatner as he explores the bizarre tales involving US presidents that defy explanation and are still shrouded in mystery. (S4, ep 4)
Throughout history, tales of inexplicable maladies have stirred morbid curiosity - from mysterious wounds to a madness that compels people to dance. (S4, ep 5)
There are many puzzling artefacts from around the world, challenging everything known about the technological capabilities of distant ancestors. (S4, ep 6)
For centuries, mankind has devised ingenious ways to hide information, from enigmatic puzzles to secret symbols. Can we unlock these great mysteries? (S4, ep 7)
Throughout history's largest and deadliest human conflict, a number of intriguing and persistent mysteries were born - from lost gold to secret societies. (S4, ep 8)
...With William Shatner. Monsters Among Us: Tales of monsters and beasts have always sparked both fascination and fear - but do these stories possess elements of truth? (S4, ep 9)