Legendary spy and art restorer Gabriel Allon is poised to become the chief of Israel's secret intelligence service. But on the eve of his promotion, ISIS detonates a massive bomb in the Marais district of Paris, and a desperate French government wants Gabriel to eliminate the man responsible before he strikes again. They call him Saladin, a terrorist mastermind so elusive that even his nationality is unknown. Shielded by sophisticated encryption software, his network communicates in total secrecy. Gabriel has no choice but to send in agent Natalie Mizrahi, an extraordinary young doctor, posed as an ISIS recruit-in-waiting and ready to serve as his black widow out for blood.