The UnXplained season 6 episode 8
Episode title: Unbreakable Codes
There's nothing more fascinating than a code that can't be cracked. For centuries, mankind has devised ingenious ways to hide valuable information using everything from enigmatic puzzles, to complex ciphers and secret symbols. If history's unbreakable codes can be deciphered, could we unlock answers to some of the greatest mysteries of both the past and present?
