Margery

Introverted backpacker Jeremy wanders off trail and discovers an eccentric, otherworldly town nestled in a mountain basin.
The people he finds there are pleasant, but a little bit peculiar. He befriends a reticent doctor and his wife, who is struggling with dementia, and Margery, who regularly leaps from a cliff in death-defying bungee jumps.
Why, he wonders, do the otherwise healthy and upbeat townspeople seem to be disappearing?