The Devil's Guard by Talbot Mundy — Read

It was not long before we learned that we had failed to throw spies off the scent. That night we sat up late discussing Tibet with Will Hancock, who had a surprising amount of information about the country. We did not admit to him that we intended to make our way over the border, he being one of those conscientious men who would have felt obliged to inform the government of anything he actually knew. But he is no man's fool; he answered all our questions without committing any such indiscretion as to ask us questions in return.

Will Hancock's chief anxiety was the season of the year. It was already autumn: the monsoon was likely to break at almost any time, after which the valleys and all the lower slopes of the Himalayas would be deluged, and the upper passes would be blocked with snow. However, he had other reasons for instilling caution: "Some people enjoy disobeying governments," he said, blinking at us through his horn-rimmed spectacles. "But up in Tibet they have made a cult of disobedience to God! It is a lie that there is any pure philosophy or pure religion up there. What there is, is sorcery--black magic--the same evil that the witch of Endor practised and that brought Sodom and Gomorrah to their ruin--that alliance with the powers of evil that the Apostle Paul denounced. With all my heart I would advise any one against trespassing in Tibet."