From steamy jungles to dry deserts, amphibians have taken their first footsteps onto land using their bizarre life histories to break their ties with the water and invade the earth.
This episode delves into the extraordinary and intimate lives of the soft skinned amphibians. This includes the marsupial frogs, a peculiar species where the father carries his young in pouches and then gives birth. It also features warring giant salamanders over a metre long and show-off newts that offer displays just like underwater birds of paradise.

David Attenborough reveals the fascinating lives of snakes, the most misunderstood group of reptiles. A CCTV stakeout of wild rattlesnakes hunting shows, for the first time, what sophisticated predators they truly are. Attenborough is also on the receiving end of a spitting cobra's chemical weapons system, while the surprisingly beautiful and tender side of snakes is displayed in the sinuous courtship of kingsnakes, and the water birth of 15 beautiful yellow anaconda babies.

The world of the armoured creatures is equally fascinating and bizarre. Galapagos giant tortoises solve the problem of making love in a suit of armour; a heated sea turtle orgy leaves females in mortal danger and we witness the explosive arrival of a baby pig-nosed turtle. Giant salt-water crocodiles crowd a flooded river-run to fish for mullet and a caiman leads her brood in a touching trek to a communal crèche.

Dr Iain Stewart investigates the counter-attack that was launched by the global warming sceptics in the 1990s. At the start of the 1990s it seemed the world was united. At the Rio Earth summit the world signed up to a programme of action to start tackling climate change. Even George Bush was there. But the consensus didn't last.
Iain examines the scientific arguments that developed as the global warming sceptics took on the climate change consensus. The sceptics attacked almost everything that scientists held to be true. They argued that the planet wasn't warming up, that even if it was it was nothing unusual, and certainly whatever was happening to the climate was nothing to do with human emissions of greenhouse gases. Iain interviews some of the key global warming sceptics, and discovers how their positions have changed over time.

Dr Janina Ramirez shows how medieval manuscripts gave power to the king and united the kingdom in an age of plague, warfare and rebellion, discovers that Edward III used the manuscripts he read as a boy to prepare him for his great victory at the battle of Crecy and reveals how a vigorous new national identity bloomed during the 100 Years War with France. In the British Library's Royal Manuscripts collection Dr Ramirez finds out that magnificent manuscripts like the Bedford Hours, taken as war booty from the French royal family, were adapted for the education of English princes. She also explores how knowledge spread through a new form of book - the encyclopaedia.

Having explained the science behind global warming, and addressed the arguments of the climate change sceptics earlier in the series, Dr Iain Stewart concludes the series by looking at the biggest challenge now facing climate scientists - Just how can they predict exactly what changes global warming will bring?
It's a journey that takes him from early attempts to model the climate system with dishpans, to supercomputers, and to the frontline of climate research today: Greenland. Most worryingly he discovers that scientists are becoming increasingly concerned that their models are actually underestimating the speed of changes already underway.