Old and young go head to head for the fourth series of Bear Grylls epic survival show. With just the clothes on their backs and a handful of basic tools, which generation has what it takes to survive when pushed to the limits of human endurance?

It's been 48 hours since the men had a meal and hunger grips the group. The race is on to bring food back to camp before they become too weak to hunt. The men take greater and greater risks in the pursuit of vital calories, desperate to seek new ways to chase, trap and outsmart the island's elusive wildlife. Ryan lashes out in anger and Craig is left deflated. And then they come face to face with one of the island's most fearsome predators - the caiman crocodile.

Three weeks into their survival experience and the group is barely getting by on a meagre diet of snails and coconuts. Willing to take ever greater risks for food, Mike and Chris battle with dangerous tides, while tempers fray as it appears that not everyone is pulling their weight. Frustrated by their failure to find another caiman croc, a hunting party risks a trip to the treacherous mangroves at night.

The men enter their fourth week of living on the island with the group hungry and divided. They elect an island leader. But will everyone back him? With island life starting to fall apart, even when a stingray arrives in the fishing nets, arguments follow close behind. But as their time on the island draws to a close and a return to civilisation beckons, there are moments of redemption for some.

Bear Grylls visits the men at the end of their stay on the Island to explore how they coped and how the experience has affected them. Bear also reveals the secrets of how the show was made, with a unique behind-the-scenes look at managing the medical risks to maintaining camera kit in extreme conditions. Bear gets to see first-hand how the men have been living for the past four weeks. He tours the camp and reflects with the men on their personal approaches to surviving. When pushed to the very limit, what did they learn about themselves and each other?

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After being dropped off on the island by Bear, the men are in danger of being overwhelmed by the tides. Battling through the dense undergrowth, the enormity of the task ahead dawns on them. As they try to get to know each other, daylight is quickly fading and tempers fray as doubts set in during the search for shelter for the night. With dehydration and hunger taking hold, the men are up against it. They need to find water and make fire or their time on the island will be over. The battle for survival is on.

With the men losing weight on a diet of just 300 calories a day, Ryan heads off alone in search of food. But without water, he soon finds himself lost and in imminent danger. With Ryan's actions now affecting the whole group, the men have a choice. Do they bring him back into the fold? Or do they cast him out?

The men have barely slept or had a real meal since landing. And a bitter rivalry between the island's two builders, Paul and Andy, has turned into all-out war.

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The young group's campsites turns into a swamp in the rain. They join up with the orders but immediately there's a row. Freddie kills a snake, and Kaggy goes on a turkey hunt.

With the old and young living side by side, the islanders hope to hit their stride. But hunger and frayed tempers lead to bust-ups as the islanders turn on one of their own.

The men come face to face with a fearsome predator. And, as the group's body weight and energy levels plummet, there's division and conflict in the camp.

The men build a raft to go fishing. But, as Vic gets dragged towards razor-sharp rocks, he faces a life and death struggle to turn the raft around.

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The camp has split in two and is dangerously low on water. As the main group head into the jungle, looking for lost members, they're in for a nasty surprise.

Malnourished, exhausted and under pressure, the group turn on each other. Vic and Sam argue, while a fishing venture goes disastrously wrong for Will.

The men swim ashore. Hammered by a succession of tropical storms, they must find a safe place away from deadly scorpions, snakes and caiman crocodile. And less than a week in, a fierce row breaks out.

Bear Grylls abandons 14 women on a desert island in the Pacific. As night falls on Day 1, they make camp in the jungle - at the mercy of deadly creatures and voracious sand flies.

The extreme conditions are taking their toll, with the women on the brink of starvation. Lauren, Beth and Belinda go pig hunting in the jungle.

It's almost four weeks into the experiment and the women are entering dangerous medical territory. They're given a 36-hour deadline to turn things around.

After five weeks on the island, the men are low on food and energy. They make a last bid to hunt for food before Bear arrives to take them back to civilisation.

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