For the animals in the polar regions, autumn means dramatic battles and epic journeys. Time is running out - the Arctic Ocean is freezing over and the sea ice is advancing at 2.5 miles per day around Antarctica. Polar bears gather in large numbers on the Arctic coast as they wait for the return of the ice. Soon, tempers fray and violent sparring contests break out. Meanwhile 2,000 beluga whales head for one special estuary, a gigantic 'whale spa' where they will thrash their snow-white bodies against the gravel and exfoliate. Inland, the tundra undergoes a dramatic transformation from green to fiery red. Here, musk ox males slam head-first into each other with the force of a 30mph car crash as they struggle to defend their harems. Frisky young caribou males play a game of 'grandma's footsteps' as they try to steal the boss's female. Down in Antarctica, Adelie penguin chicks huddle together in creches. When a parent returns from fishing, it leads its twins on a comical steeplechase - sadly there's only enough for one, so the winner gets the meal. Two months later and the chicks are fully feathered apart from downy Mohican hairdos - they're ready to take their first swim - reluctantly though, as it seems penguins are not born with a love of water! And with good reason - a leopard seal explodes from the sea and pulls one from an ice floe, a hunting manoeuvre that has never been filmed before. As winter approaches and everyone has left, the giant emperor penguin arrives and makes an epic trek inland to breed. The mothers soon return to the sea leaving the fathers to hold the eggs and endure the coldest winter on earth.

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.

The tour was designed by Willie Williams, who has worked on every U2 tour since 1982. Williams had been toying with ideas for 360-degree stadium staging for U2 for a number of years, and presented sketches of a four-legged design to the group near the end of their Vertigo Tour in 2006. The inspiration for the 'spaceship-on-four-legs' design, nicknamed 'the Claw', came from the landmark Theme Building at Los Angeles International Airport.

The second programme deals with the mechanics of flight. Getting into the air is by far the most exhausting of a bird's activities, and Sir Attenborough observes shearwaters in Japan that have taken to climbing trees to give them a good jumping-off point. The albatross is so large that it can only launch itself after a run-up to create a flow of air over its wings. A combination of aerodynamics and upward air currents (or thermals), together with the act of flapping or gliding is what keeps a bird aloft. Landing requires less energy but a greater degree of skill, particularly for a big bird, such as a swan. Weight is kept to a minimum by having a beak made of keratin instead of bone, a light frame, and a coat of feathers, which is maintained fastidiously. The peregrine falcon holds the record for being fastest in the air, diving at speeds of over 300 km/h. Conversely, the barn owl owes its predatory success to flying slowly, while the kestrel spots its quarry by hovering. However, the true specialists in this regard are the hummingbirds, whose wings beat at the rate of 25 times a second. The habits of migratory birds are explored. After stocking up with food during the brief summer of the north, such species will set off on huge journeys southwards. Some, such as snow geese, travel continuously, using both the stars and the sun for navigation. They are contrasted with hawks and vultures, which glide overland on warm air, and therefore have to stop overnight.

This episode examines those birds whose sustenance comes from flesh and their methods of hunting. In New Zealand, Sir Attenborough observes Keas, parrots that do not eat meat exclusively, raiding a shearwater's burrow for a chick. However, it is the dedicated birds of prey, such as owls, buzzards, eagles, falcons and vultures, to which much of the programme is devoted. In order to spot and pursue their victims, senses of sight and hearing are very acute. Vultures are the exception, in that they eat what others have left, and once a carcass is found, so many birds descend on it that the carrion seems submerged beneath them. The Turkey Vulture is an anomaly within its group, as it also has a keen sense of smell. Eagles defend their territory vigorously, and a pair of sea eagles are shown engaging in an aerial battle. The Galápagos Hawk hunts Marine Iguanas, but can only do so when its quarry is vulnerable, during the breeding season. The African Harrier Hawk has adapted to extracting burrowing animals by virtue of an especially long, double-jointed pair of legs. By contrast, a shrike is not equipped with the requisite sharp beak and talons needed for butchery, and so dismembers its kill by impaling it on the thorns of acacias. The Lammergeier eats bones, and will drop them on to rocks from a great height in order to break them down to a digestible size. Also featured are the Eurasian Sparrowhawk, Goshawk and Peregrine Falcon.

The second episode is about how plants gain their sustenance. Sunlight is one of the essential requirements if a seed is to germinate, and Attenborough highlights the cheese plant as an example whose young shoots head for the nearest tree trunk and then climb to the top of the forest canopy, developing its leaves en route. Using sunshine, air, water and a few minerals, the leaves are, in effect, the "factories" that produce food. However, some, such as the begonia, can thrive without much light. To gain moisture, plants typically use their roots to probe underground. Trees pump water up pipes that run inside their trunks, and Attenborough observes that a sycamore can do this at the rate of 450 litres an hour — in total silence. Too much rainfall can clog up a leaf's pores, and many have specially designed 'gutters' to cope with it. However, their biggest threat is from animals, and some require extreme methods of defence, such as spines, camouflage, or poison. Some can move quickly to deter predators: the mimosa can fold its leaves instantly when touched, and the Venus flytrap eats insects by closing its leaves around its prey when triggered. Another carnivorous plant is the trumpet pitcher that snares insects when they fall into its tubular leaves. Attenborough visits Borneo to see the largest pitcher of them all, Nepenthes rajah, whose traps contain up to two litres of water and have been known to kill small rodents.