Africa's terrorist group Boko Haram is responsible for hundreds of kidnappings -- even since the stunning 2014 abduction of nearly 300 Chibok schoolgirls. Everyone from Michelle Obama to Malala Yousafzai got involved in the hashtag campaign to "Bring Back Our Girls" -- a slogan that now is the title of a new book by Joe Parkinson, a definitive account of the incident and its aftermath.