Escape from Kathmandu by Kim Stanley Robinson
A laugh-out-loud romp through the Himalayas from the worldwide bestselling author of the Mars series
The Great Mysteries of Nepal are in danger of being uncovered and destroyed: George and Fred are hanging out in Nepal, trekking, climbing and generally having a good time. Before long they find themselves caught up in some weird schemes: rescuing a real, live yeti from a bunch of deranged scientists; scaling Mount Everest; saving the mystical city of Shangri-La and the extraordinary Kingdom Underground.
On the way they're chased by the US Secret Service, join forces with a 431-year-old Tibetan and almost start World War III...