The Internet is an uncontrollable labyrinth of content and imagery that operates under loose laws and partial anonymity - a new frontier where people can do anything and see anything, whether they should or not. In this lawless landscape, who's in control? The protectors? The abusers? In this episode meet the content moderators who watch the worst of the Internet so you don't have to; a convicted hacker whose punishment was the virtual prison of the unplugged; plus, a blackhat hacker who encrypts and holds computer files hostage.

Are the wealthy just born in the right place at the right time? Are the poor victims of a system designed to keep them down? Or do physics and biology determine who is rich and who is poor? Throughout history, distribution of wealth is governed by hidden forces: DNA, environmental stress, patterns of human migration and even the laws of thermodynamics! Nature seems to demand winners and losers in life. But does this mean greed is king, and the rich can take what they want? Or is cooperation – between microorganisms, monkeys, and humans – more essential to survival of a species?

Playing with Nuclear Fire' - In March 2011, the Tohoku earthquake in Japan created a tsunami that killed some 16,000 people and crippled the Fukushima Daiichi nuclear power plant. In the aftermath, the government and TEPCO, the plant's operator, withheld information about the extent of the damage. Three years later, citizens and the international community are left wondering if Japan really does have the situation under control, as the government is insisting, or if the danger is far greater than anyone is willing to admit. 'No Man Left Behind' - It's estimated that over a quarter million vets from recent wars have sought treatment for PTSD. Despite these statistics, veterans often face an uphill battle to get treatment, receiving inadequate attention and, most dangerously, overprescribed narcotics and other pharmaceuticals. Ryan Duffy meets veterans struggling with mental illness and addiction.

In ‘Why Do I Need You?’ Dr. David Eagleman explores how the human brain relies on other brains to thrive and survive. Our fundamentally social nature can hold the key to our sucdess as a species. Our brains are so fundamentally wired to interact that we are something more like a single vast super-organism. In this age of digital connection, we desperately need to understand how human brains interact if we want our civilization to have a future, if we want to avoid fanaticism and to embrace cooperation. This neural interdependence begins at birth. Dr. David Eagleman invites a group of babies to a puppet show to showcase their ability to discern who is trustworthy, and who isn’t.

Bladderwort utricularia is a pond-dweller that is among the fastest known, its traps snapping shut in less than a millisecond. As the seasons change, David demonstrates how plants operate on a different time scale to us; how they modify their lives according to the time of year. We discover insects’ hidden links with plants, both as pests and pollinators. UV-sensitive 3D cameras reveal the invisible alter-ego of plants and their flowers’ mesmerizing patterns; a parallel-dimension of strange colours and stunning patterns through which plants communicate with them. With the aid of visual effects, David steps among the swirling vortices of plant scent; communication signals with which plants are inextricably plugged in to the natural world. And using a tuning fork, he demonstrates how plants and insects can even communicate with music. As autumn envelopes the Gardens, fungi reveal themselves not as the enemies of plants but their vital allies. In Kew’s atmospheric Fungarium, David discovers a specimen that has the power of mind control and another that lives underground where it has grown to be so big it can be counted as the largest single organism on the planet. It is 6 times bigger than Kew Gardens itself.

An astonishing close encounter with some of the most exotic creatures inhabiting the hidden depths. In the realm of the giant octopus, the rainbow nudibranch (sea slug), and the Scorpion fish, viewers become a fearless undersea explorers, discovering the strange and unusual partnerships these 'star wars' creatures forge to ensure their survival, and learning how this cooperation allows life in this enchanting world to flourish. Filmmaker Howard Hall guides an astonishing adventure. Johnny Depp and Kate Winslet narrate as Green Sea Turtles gather so Surgeonfish can strip harmful algae from their shells. A Humboldt Squid changes color four times per second like a flashing strobe light. A Mantis Shrimp’s claws have the speed of a bullet in battling a hungry octopus. Brace yourself to be submerged in a wondrous new dimension.