Siberia

Five young British men take on the challenge of a lifetime - to spend four months travelling the world, taking on some of the most deadly creatures and hostile places on the planet.

Continuing their epic journey they travel to the Siberian arctic to become Evenki reindeer herders, a people who have survived in one of the most hostile locations for thousands of years. This is about learning to deal with extreme cold without home comforts.

The Brits arrive in a world that is lifted straight from the ice age, but for locals it is what they call spring. It is one of the busiest times of year, when reindeer herds need to be corralled and moved to new pastures. The boys have just six days to prove themselves to their trainer for the week, Evenki herder Nikolai Mikhailovich.

To become Evenki they must learn to control a reindeer sledge, the only reliable form of transport in a place where motor vehicles crack and fuel freezes. If they satisfy Nikolai they will travel out to the herd, making camp in bone-snapping temperatures and attempting to fish through a metre of ice. If they come through it all they face the ultimate challenge of staying out all night, guarding Nikolai's herd from local wolves.

After his experience in Ecuador will veggie Ben cope when there is only meat on the menu again? Has Easton recovered from his altitude sickness and his injured pride, and can Reuben learn not to ignore everything his trainer says?