Plot: Mark Beaumont, who broke the record for pedalling around the world, is back on the road, attempting to cycle from Alaska, USA, to Ushuaia in southern Argentina; traversing the length of the Rockies and Andes, 13,000 miles through 12 countries. With 8,000 miles under his belt, the final episode sees Mark battle mentally and physically through the harsh, beautiful and imposing landscapes of South America