The Stone Heart of Shambala

An old school friend invites the protagonist to his home in Ghorka, Nepal. After a few months staying there, his friend returns for a while to England leaving Mark in Nepal. The world is hit by powerful solar storms which knock out everything electric. His friend, Sabin, has to return to Nepal come what may, so he begins a journey on foot across Europe, where he meets a fellow Nepalese, and they join company. Their journey is hastened when they are picked up by a Sikh pilot in a small plane returning to India. Taking advantage of lulls in the solar storms, they hop across the Middle East until they reach India. The plane cannot continue, so they split up on foot, with the pilot heading to his home, while the two Nepalese men head for theirs.
At last Sabin finds himself in Kathmandu, where he leaves his friend and picks up a small packet of seeds from the Post Office. Shortly after, he arrives in Gorkha where his wife and Mark are waiting for him. No sooner has he rested, than a group of Tibetan monks arrive in the village carrying messages to the Dalai Lama in India. They also carry one for Sabin, from his uncle in a monastery near Mount Kailash. His uncle requests his presence, so Mark and Sabin leave on horseback and head into the Himalayas.
After a long and arduous journey they arrive at the monastery, where the monk asks them to take a message to a monastery further north which is unknown to the Chinese, and not on any map. They set off into the mountains, and find themselves sheltering in a cave from a terrible snowstorm. Coming out of the cave in the morning, a group of unusual rescuers are waiting to take them to their destination. A walk through a tunnel in a mountain, leads them to a hidden valley of warm sunshine and green fields.