Bears drops the 16 castaways in caiman-infested mangroves and deep water. The two teams with different income levels soon meet, and it quickly becomes clear that the island isn't their biggest challenge, as the prospect of living together kickstarts a class war.

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?

In the ultimate test of endurance, Bear Grylls abandons two groups - one of eight men, the other of eight women - to see if they can survive on an uninhabited island armed with just the clothes they stand up in and a few basic tools. The two groups were left at opposite ends of the same island, with neither group knowing of the other's presence.

Following complaints about the absence of women in the first series, two groups, 14 men and 14 women, were left on two separate islands for six weeks.

Adventurer Bear Grylls abandons 13 British men on a remote, uninhabited Pacific island. In danger of being overwhelmed by the tides, they battle through the dense undergrowth as the enormity of the task ahead quickly dawns on them.