In the last of the series, Julian Richards uncovers new information from the battle in 1066 between Viking warlord Harald Hardrada and King Harold of England that marked the end of the Viking age in Britain. Results from a nationwide genetic survey show where in Britain the Vikings left a measurable contribution.

The global cyberwar is heating up and the stakes are no longer limited to the virtual world of computers. Now, thanks in part to secret documents released by Edward Snowden, the true scale of the National Security Agency's scope and power is coming to light. Besides spending billions of dollars to ingest and analyze the worlds' electronic communications, the NSA has set out to dominate a new battlefield—cyberspace. We examine the science and technology behind cyber warfare and asks if we are already in the midst of a deadly new arms race". Already, highly sophisticated, stealthy computer programs such as the notorious Stuxnet worm can take over and even destroy the control systems that regulate everything from food factories to gas pipelines, power plants, and chemical facilities—even our cars. While the destruction of Iranian centrifuges may have delayed Iran’s bomb program and forestalled an Israeli attack, the attack has opened a Pandora's Box, and now America's own critical infrastructure is vulnerable to retaliation and attack. With leading defense experts and investigative journalists who have probed the murky realm of criminal and strategic hacking, NOVA examines the chilling new reality of cyberwar in which no nation or individual is safe from attack.

We all project images of ourselves online - a curated identity that defines how we want to be perceived. But what temptations exist to embellish and what are the dark implications? In this episode, enter the world of Cyberbanging, where inner city youth are using social media to brag, conspire and incite violence; two African-American women bloggers who have turned the table on the trolls who threaten them; and the creator of Abdullah X, an online character who's trying to keep Muslim kids from falling under the spell of Islamic extremists.

The first second of the Universe, the creation of everything when space, time, matter and energy burst into existence. It is the most important second in history, which seals the Universe's fate and defines everything that comes after - including us.

Nearly half a million years ago, the most advanced human yet roams Europe. Strong and powerful, Homo heidelbergensis are fierce hunters, use sophisticated tools and live in close-knit family groups. Over 200,000 years they become split into two populations by extremes of weather and environment and evolve separately into two very different species. In the North are the Neanderthals, whose physical power and resilience is the key to surviving in ice age Northern Europe. About 140,000 years ago, Africa is in the grip of a devastating drought, and something remarkable has happened to the descendants of heidelbergensis who live there. The combination of environment and chance has bred in them a unique ability that will change the course of human history. It will be this small band of southern survivors, perhaps numbering just a few tens of thousands, who will come to dominate the world and be known as Homo sapiens.

He was stalked, attacked and left to die alone. Murdered more than 5,000 years ago, Ötzi the Iceman is Europe’s oldest known natural mummy. Miraculously preserved in glacial ice, his remarkably intact remains continue to provide scientists, historians, and archeologists with ground-breaking discoveries about a crucial time in human history.