India has banned the BBC’s two-part documentary, “India: The Modi Question.” It explores Prime Minister Narendra Modi’s role during the 2002 anti-Muslim riots that left more than 1,000 people dead. Invoking “emergency powers,” riot police have been sent to university campuses to make sure the film is not shown to audiences. The World’s Marco Werman speaks to Rana Ayyub, the author of “Gujarat Files: Anatomy of a Cover Up.”