A Guardian and a Thief by Megha Majumdar

In a near-future Kolkata beset by flooding and famine, Ma, her two-year-old daughter Mishti, and her elderly father Dadu are just days from leaving the collapsing city behind to join Ma's husband in Ann Arbor, Michigan. After procuring long-awaited visas from the consulate, they pack their bags for the flight to America. But in the morning they awaken to discover that Ma's purse, with all the treasured immigration documents within it, has been stolen.