Fiction by Leise O'Halloran Schwarz
Beatrice and Laura Preston are grown-up sisters who have been at odds with each other most of their lives. The family has never been the same since Philip, the third Preston sibling, disappeared at age seven while the family was living in Bangkok. That was in 1972; now in 2019 the sisters are dealing with their elderly mother's mental decline as well.
Then Laura gets a message that Philip might be found, still living in Bangkok after over forty-five years! Beatrice is sure it's a scam, but Laura is hopeful.
This was a really good book. It gave me a lot to think about, and also held my attention.