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.

Deep in the twisted roots of a giant strangler fig tree, hidden from view, lives perhaps the most bizarre nighttime creature of all. The spectral tarsier, tiny primates barely larger than a tennis ball. As darkness falls, a family of these small primates in Sulawesi ventures into the jungle to find food while protecting their babies.

In the Taurus Mountains Simon stays with descendants of the original Turks, nomads known as Yoruks, whose lifestyle is under threat from the modern world and an increasingly religious government. They're not the only minority at odds with the authorities in Turkey; Simon sees first-hand the devastating effects of fighting in the country's Kurdish region. In an area where the government has detained foreign journalists, Simon gathers unique footage in the aftermath of a crackdown on Kurdish militants - the wholesale destruction of the historic centre of one of Turkey's oldest cities.
Away from the conflict in the south, Simon heads towards the Black Sea coast. He meets a wildlife conservationist protecting Turkey's population of brown bears, and villagers who still communicate over long distances using an ancient bird language. In the country's capital he meets a victim of President Erdogan's authoritarian purge of people accused of complicity in the failed coup against him.
Finally Simon's journey comes full circle when he returns to Istanbul - home to the new craze of 'Ottomania', a celebration of the vast empire that preceded modern Turkey. Simon visits the set of one of the world's most popular TV dramas - even getting a speaking role - based in the court of an Ottoman sultan

With much of it covered in ice all year round and with no daylight from October to March, the Arctic Ocean is one of the world's most remarkable oceans. Its home to a multitude of unique life forms, all highly adapted to cope with the extreme and seasonal conditions. The impacts of climate change are more strongly felt here than anywhere else in the world.

David Attenborough reveals the surprising truth about the cold-blooded lives of reptiles and amphibians. These animals are as dramatic in combat, as colourful in their communication and as tender in their parental care as any other animals. Join giant courting crocodiles, jousting tortoises and bright red sumo-wrestling frogs in their sophisticated, solar-powered lives.

Using state-of-the-art equipment, a group of activists, led by renowned dolphin trainer Ric O'Barry, infiltrate a cove near Taijii, Japan to expose both a shocking instance of animal abuse and a serious threat to human health". The Taiji dolphin drive hunt is a dolphin drive hunt that takes place in Taiji, Wakayama in Japan every year from September to March. According to the Japanese Fisheries Research Agency, 1,623 dolphins were caught in Wakayama Prefecture in 2007 for human consumption or resale to dolphinariums, and most of these were caught at Taiji. The annual dolphin hunt provides income for local residents, but has received international criticism for both the cruelty of the dolphin killing and the high mercury levels of the dolphin meat