Legendary spy, assassin, and art restorer Gabriel Allon is back and out for revenge - determined to hunt down the world's most dangerous terrorist, a shadowy ISIS mastermind known only as Saladin. Four months after the deadliest attack on the American homeland since 9/11, terrorists leave a trail of carnage through London's West End. The attack is a brilliant feat of planning and secrecy, but with one loose thread: the French-Moroccan street criminal and ISIS operative who supplied the combat assault rifles. The thread leads Gabriel Allon and his team to the south of France and to the doorstep of Jean-Luc Martel and Olivia Watson. A beautiful former fashion model, Olivia pretends not to know that the true source of Martel's enormous wealth is drugs. And Martel, likewise, turns a blind eye to the fact he is doing business with a man whose objective is the very destruction of the West.