Travel presenter and adventurer Ben Fogle gives four groups, each consisting of five members of the public, the chance to realise their dreams and conquer some of the world's most extreme environments. Embarking on a voyage of personal discovery each candidate will be tested to their limits mentally, physically and emotionally on their journey of a lifetime. The challenges the would-be explorers have to face are a gruelling hike to the lost Inca city of Choquequirao in Peru; an exhausting trek through virgin rainforest during rainy season to the Kaieteur Falls in Guyana; a punishing climb to the peak of the highest mountain in Africa, Mount Kilimanjaro in Tanzania; and an arduous voyage across Spitsbergen to Temple Mountain, one of the highest peaks in the region. The groups have to rise above altitude sickness, hypothermia, heat stroke, unusual cuisine, deadly creatures and sheer exhaustion, constantly being forced to work as a team to conquer the inhospitable environments. In these unrelenting circumstances will their extreme dreams turn into their worst nightmares?