Atlas of Unknowns is the story of two sisters. Anju is very bright, Linno is a brilliant artist. In order to win a scholarship (and more importantly, a visa to the US) Anju takes credit for Linno's artwork. She is off to New York and the opportunity to grow on her own away from her family. Back in India, Linno is also growing and learning more about her past.
I liked this book quite a bit but found myself more interested in the details of the story than in the story itself. The author touches on subjects and then moves on and I found myself wanting more on those tiny details and not that interested in the big 'mysteries' of the novel (which I found neither big or mysterious). I would have loved to hear more about what it was like to be a Christian in a Hindi/Muslim country as one example.
Overall, I would say this is a very good (but not great) book with all kinds of interesting facts about India and immigration in a post 9-11 world.