10,000 BC

The first 12 volunteers arrive at their camp and appoint a leader. The scouting party finds an abandoned camp by a lake and persuade the others to move - unaware that a second tribe will be arriving in 24 hours' time and that this is their allotted camp.

The second tribe arrives and finds that the first tribe have settled in their allotted camp.

A member of Wood camp receives bad news from home. The two tribes decide to share the fishing gear and catch 50-50. The Crays want to poach Dan, but he isn't sure whether to defect or not.

John orders Snake tribe to move to Hunt camp, but the Cray tribe has already been and cleared all the useful tools and taken all the fruits and nuts off the trees. Tempers flare as hunger and hardship take their toll, health detoriates and a divide emerges in one tribe.

The Crays get an unwelcome surprise when the Snake tribe moves in with them while their new camp is being built.

A joint tribal hunting party sets up base at Wood camp. After outstaying their welcome in the Cray camp, Snake leader John moves his remaining tribe to their new home.

Jay flies home to the UK to be with his pregnant girlfriend, the Snake tribe begin to turn on each other, and Crays contend with receding lake waters.

The tribes eat meat for the first time in weeks. The food sharing pact is endangered when both tribes hoard some to themselves.

The Crays debate whether to slaughter goats for food.

The tribes build a monument as a legacy of their experience.