“No refusal” is written on all the egg yolk-colored cabs of Kolkata, a pledge sometimes kept by the cabdrivers, but always fulfilled by the city itself. From the first time I had a chance to wander the decaying colonial city, Kolkata's been a mysterious yet open city for me, its wide sidewalks like something out of Italo Calvino’s “Invisible Cities.” I’ve always wanted to come back to dig deeper, not...