In the fourth episode of the series, legendary nature and cultural photographer Art Wolfe captures the great brown bear with the stunning backdrop of Alaska’s mountains and glaciers, immigrating wildebeests in the plains East Africa, and the hard-to-find gorillas of Uganda.

Hidden Kingdoms for the first time takes the viewer into a unique and unexplored miniature world, immersing you into the action-packed lives of the planet's smaller animals. This episode is the story of two young animals forced to grow up fast. In Africa's savannah, a baby elephant shrew learns how speed is the secret to survival amongst the largest animals on Earth; and in America, a young grasshopper mouse confronts the Wild West's deadliest creatures to stake a claim of his own

Professor Brian Cox examines how it was that in a universe made of stars, rocks and endless space, a conscious civilisation was born. His latest adventure takes him from a submerged space station in Star City on the outskirts of Moscow, to Ethiopia, high above in the Great Rift Valley, where he encounters the geladas, mankind's distant ancestors. Despite once being Africa's most successful primate, a species who at one time roamed across the entire continent, these days they are found in one just place in the remote Ethiopian Highlands. Cox investigates why these ancestors retreated, yet modern mankind has expanded across the planet.

A group of brave individuals risk their lives to save the last of the world's mountain gorillas; in the midst of renewed civil war and a scramble for Congo's natural resources." Virunga National Park in the Congo is a place of unique natural beauty. It is the home to a plethora of wonderful animals and vegetation but as is so often the way, it has several serious problems that threaten it. It's the location of human violence, corruption and exploitation. The disasters that specifically loom are two different groups, the M23 and SOCO International. The former are a violent rebel force who engages in an ongoing civil war with the Congolese government and the latter are a British energy company who specialise in oil exploration. Both M23 and SOCO invade the park in their own ways and neither seems very interested in the laws that have been set up to protect the flora and fauna that exist there, far less the people who live there. It seems hardly surprising in the case of M23, as they are a paramilitary organisation who can hardly be expected to be concerned with such things but it is the more legitimate big business SOCO who seem more worrying if anything. We discover in fact that they have been involved in a bribery campaign, utilising M23 as enforcers. It's a very murky situation where big money walks all over an impoverished nation and disregards a natural space that they can see no value in in their pursuit of financial profit.

Someone once observed: 'America is great because she is good; if she ever ceases to be good she will cease to be great.' Today that notion of the essential goodness of America is under attack, replaced by another story in which theft and plunder are seen as the defining features of American history-from the theft of Native American and Mexican lands and the exploitation of African labor to a contemporary foreign policy said to be based on stealing oil and a capitalist system that robs people of their "fair share"

At first glance, Matthew Vandyke —a shy Baltimore native with a sheltered upbringing and a tormenting Obsessive-Compulsive Disorder diagnosis— is the last person you’d imagine on the front lines of the 2011 Libyan revolution. But after finishing grad school and escaping the U.S. for 'a crash course in manhood,' a winding path leads him just there. Motorcycling across North Africa and the Middle East and spending time as an embedded journalist in Iraq, Matthew lands in Libya, forming an unexpected kinship with a group of young men who transform his life. Matthew joins his friends in the rebel army against Gaddafi, taking up arms (and a camera). Along the way, he is captured and held in solitary confinement for six terrifying months.