Shangri-la/Siddhashrama/Shambhala

[pinnacle]

Hey Guys ,
I am very curious to known about  Shangri-la mythical kingdom hidden  somewhere in Himalayas there are stories of people who shared their experiences .
There are many fictional books on this topic but recently I came across a spiritual man who talked about  Paris women named  Sophia  wrote a book in french about her experience inside Shangri-la translated into english .
Anybody know name of this book?