SOLVED. Adult Mystery. Missing person. 2 siblings arrive in Paris hotel, next morning one is gone. [s]

[Beryl]

and hotel says the sibling arrived alone there is no other sibling in room ever....later on it turns out sibling had very bad illness so they disappear person............

[Sirvantes]

This sounds like So Long at the Fair, by Anthony Thorne. It was made into a movie with the same name.

https://www.goodreads.com/book/show/3...

[Beryl]

Thanks, yes that is it.

[Sirvantes]

Yay, glad you could reconnect with it.