During a Gurkha recruitment Palin is disturbed by Maoist insurgents, but survives to suffer as he climbs to 15,000 feet and sees the majesty of Annapurna Sanctuary. In Kathmandu he is blessed by the Nepalese king before meeting some holy men. Crossing into Tibet, he meets his first yaks at the highest monastery in the world, before heading up the Rongbuk glacier towards the summit of Everest.

This is the story of three maps, three 'visions' of London over three centuries. The Morgan Map of 1682 was the first to show the whole of the City of London after the Great Fire of London. In 1746 John Rocque produced at the time the most detailed map ever made of London. Like Morgan's, Rocque's map is all neo-Classical beauty and clinical precision, but the London it represented had become the opposite. In engravings of the time, such as Night, the artist William Hogarth shows a city boiling with vice and corruption. Stephen Walter's contemporary image, The Island, plays with notions of cartographic order and respectability. His extraordinary London map looks at first glance to be just as precise and ordered as his hero Rocque's but, looking closer, it includes 21st century markings such as 'favourite kebab vans' and sites of 'personal heartbreak'.

Michael Wood charts the coming of Islam to the subcontinent and one of the greatest ages of world civilisation: the Mughals. He visits Sufi shrines in Old Delhi, desert fortresses in Rajasthan and the cities of Lahore and Agra, where he offers a new theory on the design of the Taj Mahal. He also looks at the life of Akbar, a Muslim emperor who decreed that no one religion could hold the ultimate truth, but whose dream of unity ended in civil war.

Every year grizzly bear families in North America depend for their survival on a spectacular natural event: the return of hundreds of millions of salmon from the Pacific Ocean to the mountain streams where they were born. The salmon travel thousands of miles to spawn and then die. The great run not only provides food for bears, but for killer whales, wolves, bald eagles, and even the forest itself. The question is: will the salmon return in time to keep hungry bears alive?
A mother grizzly and her cubs emerge from their den high in snowy Alaskan mountains. Filming from the air the team capture a TV first, following the bears as they negotiate a near vertical slope on their journey to the coast where they await the return of the salmon. Meanwhile, the salmon are making their way to the to river mouths where they must swim upstream and against the current. The programme reveals how they tackle the torrents and leap over waterfalls, a feat equivalent to a human jumping over a house. Dozens of hungry bears eagerly await the salmon that make it up river. In another TV first, underwater cameras record the ingenuity and fancy footwork they use to collect dead salmon from the bottom of deep pools.

Grasslands feed the world. Over thousands of years, we humans have learned to grow grains on the grasslands and domesticate the creatures that live there. Our success has propelled our population to almost seven billion people. But this episode reveals that, even today, life in the 'Garden of Eden' isn't always rosy. We walk with the Dorobo people of Kenya as they bravely attempt to scare off a pride of hungry lions from their freshly caught kill. We gallop across the Steppe with extraordinary Mongolian horsemen who were 'born in the saddle'. And in a perfect partnership with nature built up over generations Maasai children must literally talk to the birds! The honeyguide leads them to find sweet treats, but they'll have to repay the favour.

Rivers provide the essentials of life: fresh food and water. They often provide natural highways and enable us to live in just about every environment on Earth. But rivers can also flood, freeze or disappear altogether!Cities - Surviving the Urban Jungle Human Planet joins Sam Niang, a Laotian fisherman, as he walks a high wire strung above the raging Mekong River rapids on an extraordinary commute to work. There's also a look at the remarkable partnership between Samburu tribesmen and wild elephants in their search for water in the dried-out river beds of Northern Kenya. Plus, a father who must take his two children on a six-day trek down a frozen river - the most dangerous school run on Earth, and the ice dam busters of Ottowa with their dynamite solution to a city centre hold-up.