'The Coldest War': With the polar ice caps shrinking due to global warming, new trade routes are being exposed, along with billions of dollars' worth of natural-resource reserves. The five nations bordering the Arctic are readying themselves to fight for it. The problem is that there's one non-NATO country that already considers itself rightful owner of the region: Russia. With Vladimir Putin's recent military annexation of Crimea, there's a definite possibility its aggressions will boil over, returning the international community to precarious Cold War footing. We will head north to witness NATO forces participating in the largest polar military exercise in history. 'Heroin Warfare': Since the U.S. occupation of Afghanistan, heroin production in the region has skyrocketed, making the country the number-one producer by a large margin. Though Iran, Afghanistan's neighbor, is an ultraconservative country, Afghan heroin flowing across the border has actually caused Iran to have the worst heroin use problem in the world. Suroosh Alvi gets a rare look inside Iran to meet the suffering heroin addicts, and see how the country is coping with the illegal drug trade.

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.

Push the limits of your imagination as astronomers attempt to grasp the mind-boggling extremes of size, distance and speed within our universe by bringing them down to earth. In this episode, our cast uses awesome analogies to bring the biggest objects, farthest distances and fastest speeds down to earth. To truly understand the scale of the cosmos, we jump behind the wheel of monster trucks, scale the Golden Gate Bridge, and race across the desert in a rocket-powered car.

Written and presented by David Attenborough, who said: 'One of the most wonderful things about filming plants is that you can reveal hidden aspects of their lives, you can capture the moment as one plant strangles another, and as they burst into flower. But whilst time-lapse photography allows you to see things that no human being has ever seen before". David begins his journey inside the magnificent Palm House, a unique global rainforest in London. Here, he explores the extraordinary plants that are so well adapted to wet and humid environments and unravels the intimate relationships between wet zone plants and the animals that depend on them. It was in the wet zones of the world that plants first moved on to land and in the Waterlily House David reveals how flowers first evolved some 140 million years ago. Watching a kaleidoscope of breath-taking time-lapses of these most primitive of flowers swelling and blooming in 3D, he is able to piece together the very first evolutionary steps that plants took to employ a wealth of insects to carry their precious pollen for the first time. David discovers clues to answer a question that even had Charles Darwin stumped: how did flowering plants evolve so fast to go on to colonise the entire planet so successfully?

China's last empire, the Qing, lasted from 1644 to 1912. It began in violence and war as the Manchus swept down from the north, but invaders became emperors, with three generations of one family ruling the country. Among them, Michael Wood argues, was China's greatest emperor - Kangxi. Under the Qing, China doubled in size to include Xinjiang in the far west, as well as Mongolia and Tibet, creating the essential shape of China today. The new dynasty tolerated a diversity of cultures and religions, including Islam. In Kaifeng, Michael visits a women's mosque with a female imam, a delightful scene that ends with laughter and selfies! The Qing also undertook huge cultural enterprises. At a traditional printing house where the wood blocks are hand-carved, we see how the Complete Tang Poems were reproduced - all 48,000 of them. We travel through the wintry countryside to a remote village where a hardy audience watch open-air opera in the snow and visit a painter's studio, and 'storytelling' houses in Yangzhou. In the 18th century, China was arguably the greatest economy in the world, and we get a fabulous sense of the rich culture that came with prosperity. But then came the clash with the British, in the first Opium War, when a British expedition destroyed the Qing navy and extracted territory and trading rights. We leave with a glimpse of the future. 'Every dynasty has risen and declined,' says Michael, 'and has needed new life to regenerate, and this time the catalyst was the British.' Among the ports China ceded was an almost uninhabited island, Hong Kong, one of today's greatest financial centres, and Shanghai, a small town then but now one of the greatest cities in world.

Few sounds are more beautiful or moving than the underwater songs of the humpback whale. Male whales compete with their songs, which often last for 10 minutes at a time, and can be repeated for hours on end. Whales separated by thousands of miles of sea will sing almost identical songs. Researchers have found that the songs change throughout the breeding months, following a mysterious pattern repeated across the waves. Whales also use sound to hunt. To catch herring, humpback whales release a stream of bubbles to form a shimmering, circular fishing net. Emitting a repetitive loud scream, they scare the fish into a tight ball, then lunge out of the water to swallow the shoal whole. Now it seems that the long-held image of the gentle giant must change to one of a ferocious and opportunistic hunter.