We live under a billion unblinking eyes - a global surveillance system that solves crime and uncovers terrorist plots. But are we ready for a world without secrets - where not even our homes are off-limits and corporations know our every desire?

Back one million years ago, South America was a continent of exotic oversized creatures found nowhere else on Earth - huge terror birds, giant ground sloths and spiky-tailed relatives of the armadillo as big as cars. The deadliest animal of them all was smilodon, the largest of the sabre-tooth cats, with canines like carving knives. The programme follows the fortunes of an individual male, Half Tooth. Ousted from his clan by a pair of rival males, his life suddenly becomes a struggle to survive in this alien world.

The years 1825-1918 were bloody and traumatic, a period when four tsars tried - and failed - to deal with the growing pressure for constitutional reform and revolution. In 1861, millions of enslaved serfs were freed by the Tsar-Liberator, Alexander II. But Alexander paid the ultimate penalty for opening the Pandora's box of reform when he was later blown up by terrorists on the streets of St Petersburg. Elsewhere, there was repression, denial, war and - in the case of the last tsar, Nicholas II - a fatalistic belief in the power of God, with Nicholas's faith in the notorious holy man Rasputin being a major part in his undoing. Lucy Worsley also details the chilling murder of Nicholas and his family in 1918, and asks whether all of this horror have been avoided.

'It's really about terror and intimidation and people basically fighting for survival and often committing extraordinary violence in order to protect themselves or to stay safe. It's kind of like the weak dog in the pack. If others spot weakness, they're gonna pounce on you for a couple of reasons. You pounce on that guy, that gives you a little more status. So, I had to ask myself, are you gonna be a victim? No, I ain't gonna be a victim. Well, that really only left me one choice in my mind. That means I gotta be the victimizer. At some point, for some reason, might be legitimate, might not be, someone's gonna test you.. Even if you lose, you're gonna have to stand up for yourself. '
'A guy comes over, and it's your day to get your package, and he tries to take your package from you that your people sent you, if you let him do it, there's gonna be 10 other dudes, oh, yeah, he let that guy take his package, I'm gonna go get his TV, right down the line until somebody's after your ass. But if you stand up that first time and they see you'll stand up for yourself, even if you lose, people will respect that. Oh, don't mess with him. There's easier prey. Why do you have to go and get that guy and get a couple lumps for it when he can go get that guy's stuff over there, don't cost you nothing. It usually only has to happen once or twice but just as importantly that you didn't go to the man for help... you're gonna be all right.'

Lucius Vorenus, the power-hungry 'Son of Hades', controls the Aventine but practices a pointless, beastly reign of terror, coming down hard on gang captains for futilities, and nearly ruins his friendship with Pullo, whose efforts to calm things down are mistaken for disrespect and disobedience, even starts a fight once he learns the truth about Niobe; Pullio leaves Rome disgusted.
After Atia convinces Marc Antony the governorship of ghastly Macedonia after his consulate would not only be unpleasant but leave him exposed to his dangerous enemies.

A heroic congressman, Leo Joseph Ryan Jr, travels to Jonestown; some Temple members plot their escape. Jim Jones realizes the walls are closing in and plans his final stand. After the massacre, the world learns about mass murder/suicide in Jonestown, orchestrated by cult leader. Survivors try to piece their lives back together.