The Pythagorian philosopher Plato hinted enigmatically that there was a golden key that unified all of the mysteries of the universe. It is this golden key that we will return to time and again throughout our exploration. The golden key is the intelligence of the logos, the source of the primordial om. One could say that it is the mind of God. With our limited senses we are observing only the outer manifestation of the hidden mechanics of self similarity. The source of this divine symmetry is the greatest mystery of our existence.

Deep in the Bolivian Andes at the height of 13,000ft stands Tiwanaku, the awe-inspiring ruins of a monolithic temple city. Built by a civilisation who dominated a vast swathe of South America, it was abandoned 1,000 years ago. For centuries it has been a mystery - how did a civilisation flourish at such an altitude and why did it vanish? Jago Cooper journeys through Bolivia's spectacular landscape to investigate the origins of Tiwanaku and finds evidence of an ancient people with amazing understanding of their environment, whose religion was based on collective effort and ritual beer drinking.

(Click CC for Subtitles) Deep in the forests of Northern Italy resides the prized white Alba truffle. Desired by the wealthiest patrons in the world, it remains a pungent but rarified mystery. It cannot be cultivated or found: the only souls on Earth who know how to dig it up are a tiny circle of canines and their silver-haired human companions-Italian elders with walking sticks and devilish senses of humor-who only scour for the truffle at night so as not to leave any clues for others. Still, this small enclave of hunters induces a feverish buying market that spans the globe.
With unprecedented access to the elusive truffle hunters, filmmakers Michael Dweck and Gregory Kershaw follow this maddening cycle from the forest floor to the pristine restaurant plate. With a wily and absurdist flare, The Truffle Hunters captures a precarious ritual constantly threatened by greed and outside influences but still somehow protected by those clever, tight-lipped few who know how to unearth the magic within nature.

Perhaps the most mysterious structure on Earth, Stonehenge has stood on a plain in Southern England for 5000 years. Its foundations predate the Great Pyramids. It is one of mankind's most ancient mysteries. Why is it here? Is it a temple? A burial ground? A place for sacrifice? Or could the mystery of Stonehenge be revealed in its builders' desire to explore the unknown heavens and touch the universe? Using the cutting-edge computer-generated imagery that takes us into deep space, we'll also go inside a virtual Stonehenge to see what the ancients saw and push this prehistoric marvel to give up its age-old secrets.
In this episode we explore the possibility that this was a prehistoric astronomical observatory. Here ancient astronomer priests may have divined the complex movements of the Sun and Moon, recognizing patterns that would not be discovered elsewhere for thousands of years. The primitive Shamans may have also been the first astronomers to predict eclipses.

The film explores George Mallory's obsession with becoming the first person to reach the highest place on Earth. Told through the explorer's poignant and evocative letters to his wife, Ruth, previously unseen photos and film archive from 1924 (restored from the original nitrate especially for the film), dramatization and a modern-day expedition retracing the original route taken in 1924, Mallory's incredible adventure lives again. The expedition was led by renowned mountaineer Conrad Anker, whose life became inextricably linked with Mallory after he found Mallory s body on Everest in 1999. Using replica 1920s-era clothing and equipment, Anker sets out to solve the great mystery of whether Mallory succeeded in summiting Everest before he died he was last seen just 800 feet from the summit before the clouds closed in and he disappeared into legend. The most heart-breaking clue: All of Mallory's belongings were found intact on his body, except the photograph of his beloved Ruth, which he promised to leave at the top of the world if he succeeded.

After four decades of searching for him, they got a one hundred percent match to the Golden State Killer's DNA. As 72-year-old former police officer Joe DeAngelo's arrest unfolds in real time, chilling facts materialize that illuminate Michelle McNamara's prescience in her book's epilogue.