We Want to Negotiate: The Secret World of Kidnapping, Hostages and Ransom

Starting in late 2012, Westerners working in Syria -- journalists and aid workers -- began disappearing without a trace. A year later the world learned they had been taken hostage by the Islamic State. Throughout 2014, all the Europeans came home, first the Spanish, then the French, then an Italian, a German, and a Dane. In August 2014, the Islamic State began executing the Americans -- including journalists James Foley and Steven Sotloff, followed by the British hostages.

Joel Simon, who in...