The fifth programme explores the alliances formed between the animal and plant worlds. Attenborough dives into Australia's Great Barrier Reef and contrasts the nocturnal feeding of coral, on microscopic creatures, with its daytime diet of algae. Some acacias are protected by ants, which will defend their refuge from any predator. Besides accommodation, the guards are rewarded with nectar and, from certain species, protein for their larvae as well. Fungi feed on plants but can also provide essential nutriment to saplings (Mycorrhiza). The connection is never broken throughout a tree's life and a quarter of the sugars and starches produced in its leaves is channelled back to its fungal partners. Meanwhile, fungi that feed on dead wood leave a hollow trunk, which also benefits the tree. Orchids enjoy a similar affiliation. Lichens are the product of a relationship between fungi and a photosynthetic associate, usually algae. They are extremely slow-growing, and a graveyard is the perfect location to discover their exact longevity. Mistletoe is a hemiparasite that obtains its moisture from a host tree, while using own leaves to manufacture food. Its seeds are deposited on another by the mistletoe tyrannulet, following digestion of the fruit. The dodder (Cuscuta) is also parasitic, generally favouring nettles, and siphons its nourishment through periodic 'plugs' along its stem. The rafflesia has no stem or leaves and only emerges from its host in order to bloom — and it produces the largest single flower: one metre across.

Filmmaker Robert Kenner lifts the veil on our nation's food industry, exposing the highly mechanized underbelly that's been hidden from the American consumer with the consent of our government's regulatory agencies, USDA and FDA. Our nation's food supply is now controlled by a handful of corporations that often put profit ahead of consumer health, the livelihood of the American farmer, the safety of workers and our own environment. We have bigger-breasted chickens, the perfect pork chop, insecticide-resistant soybean seeds, even tomatoes that won't go bad, but we also have new strains of e coli--the harmful bacteria that cause illness for an estimated 73,000 Americans annually. We are riddled with widespread obesity, particularly among children, and an epidemic level of diabetes among adults Featuring interviews with such experts as Eric Schlosser (Fast Food Nation), Michael Pollan (The Omnivore's Dilemma) along with forward thinking social entrepreneurs like Stonyfield Farms' Gary Hirschberg and Polyface Farms' Joe Salatin, the film reveals surprising--and often shocking truths--about what we eat, how it's produced, who we have become as a nation and where we are going from here.

Ron Mann investigates the miraculous, near-secret world of fungi. Visionaries Gary Lincoff and Larry Evans lead us on a hunt for the wild mushroom and the deeper cultural experiences attached to the mysterious fungi. The oldest and largest living organisms recorded on Earth are both fungi. And their use by a new, maverick breed of scientists and thinkers has proven vital in the cleansing of sites despoiled by toxins and as a "clean" pesticide, among many other environmentally friendly applications. Combining material filmed at the Telluride Mushroom Fest with animation and archival footage, along with a neo-psychedelic soundtrack by The Flaming Lips, this film opens the doors to perception, taking the audience on an extraordinary trip where the fungi might well guide humanity to a saner, safer place.

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.

Upending the conventional wisdom of why we gain weight and how to lose it, Fed Up unearths a dirty secret of the American food industry—far more of us get sick from what we eat than anyone has previously realized. Filmmaker Stephanie Soechtig and TV journalist Katie Couric lead us through this potent exposé that uncovers why—despite media attention, the public’s fascination with appearance, and government policies to combat childhood obesity—generations of American children will now live shorter lives than their parents did.

In a late Jurassic forest in what is now China, an Epidexipteryx escapes from a juvenile Sinraptor by climbing a tree. It finds a beetle grub in the tree bark, being shown to use its elongated fingers in a similar way to a modern day aye-aye. However, its prey is stolen by another, larger Epidexipteryx, and after a brief bout of posturing, the smaller individual goes to find more food. It drops a second grub to the forest floor, where the other Epidexipteryx retrieves it, only to be killed by the juvenile Sinraptor. The episode then cuts to a desert in late Cretaceous Mongolia, where a Saurornithoides is shown brooding a nest of eggs. When it leaves the nest, an Oviraptor raids it, fleeing when the troodontid returns. The Saurornithoides is suddenly attacked and eaten by a Gigantoraptor, which then heads to compete in a breeding ritual for mates. The males use their feathers for display, a brief fight between two erupting at one point, allowing the females to choose the best suitor. The episode finally cuts to an early Cretaceous forest in China, where a Xianglong is being hunted by a Microraptor, which uses its feathers to pursue the gliding lizard in the air. A Sinornithosaurus attacks it, and after a brief chase the Microraptor manages a lucky escape. The Sinornithosaurus, alongside two other members of its species is then shown hunting a Jeholosaurus and its three young. The group brings down the parent, the narrator explaining that their possibly venomous bite allowed them to tackle animals much larger than themselves. A montage is then shown of the feathered dinosaurs featured in the programme, with the narrator saying that Microraptor not only hints at how flight might have developed, but also that dinosaurs still live amongst us today, as birds.