In the first episode, the tribe is dropped into a remote forested wilderness. Waiting for them is Klint Janulis, an archaeologist and survival expert. He will help them swap their smart phones and modern clothes for animal skins and introduce them to their new home – a Mesolithic-style camp supplied with some basic tools, rations and a pile of flint. To get them started, they are given a freshly killed deer – a sudden reality check for vegetarian Josie. With only hours before nightfall, the tribe have to preserve as much food as possible, dig latrines and make a fire. Hours later, with the fire still not lit and raw meat ready to be cooked, their first night looks likely to be a very cold and hungry one…
Steve tries to get the team not to make the same mistakes that they made when they allowed the deer meat to be wasted. Paul attempt to create a boar trap whilst an unpleasant discovery is made by Kim.
With rations running low and the animal traps empty, Steve organises a fishing party. After trekking for more than three hours the hungry anglers cast their lines, but while they get many bites landing a fish proves to be difficult. Back at camp, hunger claims its first victim as Kym has to have medical help.
Day 8 sees the tribe with only enough rations for another day. When another fishing trip yields little in the way of nourishment, the condition of the tribe forces the survival experts and the producers to decide whether to intervene or halt the experiment.
Ten days in, and the tribe are still desperately low on rations as the cold weather sets in. A freak snowstorm covers the camp in two feet of snow, forcing the production team to consider evacuation.
It is Day 22 of the experiment, and the tribe have returned to camp. An argument arises over how to treat a fresh deer carcass and Steve loses control of the group.
New leader Mel is determined to conserve rations and supplement them with foraged roots, berries and fish, but Paul is determined to go hunting. JP threatens to leave when a meeting is called to discuss his laziness.
Paul and Mike continue to defy Mel and go hunting, but they return empty-handed and collapse with exhaustion in front of a group of the girls. JP demonstrates hitherto unsuspected talents.
With less than two weeks to go until the experiment is over, the tribe are subsisting on half their recommended calorie intake. Leader Mel thinks that they have enough food to last, but Paul is doubtful.
In the final days of the experiment, only five of the original 20 tribe members remain. With the recent shock departure of Paul and Mike still seriously ill, Mel finds the strain of carrying the weaker members is pushing her to breaking point.
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.
