Comedian Sue Perkins and adventurer Charley Boorman travel across Alaska to the notorious Dalton Highway - a dirt track built in the 1970s as a supply road to support the Trans-Alaska oil pipeline. Highway maintenance is a full time job here with avalanche units operating throughout the year. As Arctic conditions close in on them, the pair have to rely on the help of hardcore truckers for whom the highway is home. The rules of the road are: keep the CB radio switched on, don't exceed 50mph, and when an 18-wheel truck comes thundering down the rollercoaster of a road towards you, get out of the way!

Rhod Gilbert and Greg Davies face a variety of different unusual hazards as they travel through Nepal, a country which has one of the world's highest amounts of road traffic accidents.

Adventurer Ben Fogle and comedian Hugh Dennis drive a historic route from the Peruvian Andes to the depths of the Amazon, along roads built to conquer and exploit the natural wealth of Peru's rainforest. It's a rollercoaster ride of 2,000 foot drops and hairpin bends on one-lane dirt roads, stretching from mountains high above the clouds to the muddy, humid trails of the jungle. At the end of this epic journey they hope to find the lost city of Constitucion. To get there, they will have to endure some of the most remote and dangerous roads in South America. It's a journey that will test them both to the limit and beyond.