Levison and his guide Malang start their trek in Afghanistan's Wakhan Corridor, where few Westerners have been, before heading for the 5000-metre wall of snow and ice that leads to northern Pakistan.

Levison and Malang traverse breathtaking scenery in northern Pakistan's remote mountain valleys, meeting tribespeople and nomads, before heading to the heavily militarised frontier with India.

Levison reaches Nepal, and enters one of its least explored national parks, which is home to rhinos, tigers and 10-foot-long crocodiles. But animals aren't the only dangers he faces...

After recovering from the car crash that almost killed him, Levison returns to Nepal, where he has an emotional reunion with Binod's family, then heads towards Everest, Kathmandu and Bhutan

Levison and Binod reach Bhutan, where visitor numbers are strictly limited. They get a rare chance to experience its dramatic scenery, colourful festivals and historic monasteries and meet its people.