The murder of four people in the Hyper Cacher kosher store in Paris in January 2015 served as a wake-up call to Europe and much of the world what French Jews had known for a long time: European antisemitism was back, and with a vengeance. This attack, coming on the heels of the Charlie Hebdo atrocity, could no longer be ignored. The vicious hatred that had been bubbling just under the surface in extreme corners of Europe’s migrant community—not to mention the far-right and far-left political fringes—had boiled over. But the warning signs had been present for at least a decade, since the kidnapping, torture, and murder of Ilan Halimi.