Lucy must adapt to life as a hunter-gatherer and earn the respect of the tribesmen, whose knowledge, skills and understanding of the land will be vital for the expedition ahead.

Halfway through their trek, Lucy and the team face dense forests and the ever-present threat of elephants, as rations run dangerously low.

The team enter the Serengeti where lions roam free and danger is always near. With water running out, their final challenge awaits.