Kate Humble investigates how tough life is for an Afar woman; Steve Leonard wants to learn about the relationship between the Afar and their animals, and to help with animal medicine where he can; Dr Mukul Agarwal looks at the health issues faced in this most hostile of environments; earth scientist Dougal Jerram looks at the extraordinary volcanic activity of the region and the part it plays in the bigger geological picture of the Rift Valley; and biologist Richard Wiese searches for extreme life forms in the boiling soil of a massive volcanic fissure.

Kate Humble and a team of experts now face their biggest challenge of all - a climactic descent into the crater of Erte Ale volcano, with its swirling lake of boiling lava.

Kate Humble and her team say goodbye to the Afar tribe. Meanwhile, back at the volcano, earth scientist Dougal Jerram continues his mapping of the volcanic crater and biologist Richard Wiese wraps up his search for extreme life forms in the boiling soil of a massive volcanic fissure.