I honestly don't know where to begin. It is such a thought-provoking work!
Spoiler alert - I will be talking directly about what the book made me think about. However, in this case, I feel that it might be overlooked, even if you haven't read it yet, since we are actually talking about a news report!
At first glance, "Behind the beautiful forevers" seems to be a fictional narrative about a slum, called Annawadi, that is situated very near a Mumbai airport. The story revolves around several families in Annawadi, and how they get by. The characters and events seem to be constructed to tell a particular story, however, it turns out that the whole work is an extended report by a journalist. Katherine is a journalist for "The New Yorker", and has spent her professional career by reporting from areas of extreme poverty. After she got married in India roughly some ten years ago, she took on herself the project of telling the story of an average Mumbai undercity. She spent three years in Annawadi (2008-2011), and all the names, events, motivations, psychology etc. are factual (to the extent the truth can even be ascertained in such a context - the author's note at the end of the book sheds some light on the subject).