A young mother's mysterious death and her son's subsequent kidnapping blow open a decades-long mystery about the woman's true identity and the murderous federal fugitive at the center of it all.
It's late at night in Oklahoma City, in April of 1990. Two or three guys are in a truck driving along the road and they see some kind of debris. And then they see off to the side, there's a body. It appears to be a young woman, a blonde-haired woman and they call an ambulance. She's rushed to the hospital, and her husband, Clarence, eventually shows up. He says her name is Tonya Hughes, that she's a stripper in Tulsa, and that they have a young son named Michael. And he's much older and he's just kind of this weird guy. So, the doctors, as they continue to examine her, they see old bruises and old injuries. There's something wrong with this picture. Ultimately, she passes away. The girls Tonya danced with want to find her family. So they call this woman and they tell her that her daughter died. And she says, 'What are you talking about? My daughter died 20 years ago, she was only 18 months old.' They realize that who they just buried was not Tonya Hughes, so now they're asking, 'What happened?'.

Moving on to Ethiopia 3.2 million years ago, we witness the beginnings of mankind via a group of australopithecus - a type of ape which, like us, walks upright on two legs. But unlike us, these early members of the human family weren't predators, they were prey. Things get worse for the group as they are hunted by a sabre-tooth cat called dinofelis and fall victim to other dangers such as malaria, rival australopithecus and a rampaging 14-tonne deinotherium.

A child lies on the rug of a tenement dreaming of interstellar adventures. At the dawn of the space age, a young Carl Sagan’s career is forged in the clash of his mentors, two scientific titans. Sagan goes on realize his childhood dreams, to carry their research forward and communicate its significance to the whole world.

The tale of the strongest superhero in Greek mythology and his quest for redemption. To atone for committing a heinous crime, Hercules embarks on a series of impossible challenges known as the 12 Labors. Hercules endures as one of history's most influential demi-Gods, but recent archaeological discoveries suggest that mythology's strongest man may have been inspired by a real person.

Located beneath Russia's Ural Mountains, Orda Cave is legendary among divers for its unique beauty. The cave's waters are clearest in winter, when the land above lies frozen. With temperatures approaching minus 40 degrees, NHK attempts to film the cave for the first time ever using 4K cameras. Scientists give them insight into the cave's origins, enabling the crew to uncover the miraculous story of how the cave was naturally formed 300 million years ago by climate change and a shifting landscape.

The deep is perhaps the most hostile environment on earth, at least to us - a world of crushing pressure, brutal cold and utter darkness. We have barely begun to explore it, and yet it is the largest living space on the planet. Scientists already think that there is more life in the deep than anywhere else on earth. This episode takes us on an epic journey into the unknown, a realm that feels almost like science fiction. We discover alien worlds, bizarre creatures and extraordinary new behaviours never seen before. We encounter savage hordes of Humboldt squid hunting lanternfish in the depths and coral gardens flourishing in absolute darkness, with more species of coral to be found in the deep than on shallow tropical reefs. Narrated by David Attenborough.