Four westerners are kidnapped from the subcontinent when the aeroplane in which they are fleeing Baskul in India is quietly hijacked and crash landed in the Kunlun Mountains of northern Tibet. The four are taken to the valley of the Blue Moon, to the lamasery of Shangri La, where their nominal low key leader, a survivor of the horrors of World War I, experiences a spiritual awakening of sorts. Hilton captures the somewhat detached, out of body experience that can accompany altitude, and the mindfulness allowed by the vast emptiness of the Himalayan steppe.
Published in 1933, Lost Horizon dates from the time when Tibet was an independent kingdom, still full of mystery and isolated from the western world. The novel naturally shows some signs of its age, in particular the post Great War setting, but remains very readable.
Wikipedia page: Lost Horizon – James Hilton