The bomb itself was a marvel of design and construction. It was not the kind of device built from Internet manuals or the how-to pamphlets floating around the Salafist mosques of Europe. It had been perfected under battle conditions in Palestine and Mesopotamia. Packed with nails soaked in rat poison—a practice borrowed from the suicide bombers of Hamas—it carved through the crowd like a circular saw. So powerful was the explosion that the Louvre Pyramid, located a mile and a half to the east, shivered with the blast wave. Those closest to the bomber were blown to pieces, sheared in half, or decapitated, the preferred punishment for unbelievers. Even at forty paces, limbs were lost. At the farthest edge of the kill zone, the dead appeared pristine. Spared outward trauma, they had been killed by the shock wave, which ravaged their internal organs like a tsunami. Providence had granted them the tender mercy of bleeding to death in private.

The first gendarmes to arrive were instantly sickened by what they saw. Extremities littered the paving stones, along with shoes, smashed wristwatches frozen at 11:46, and mobile phones that rang unanswered. In one final insult, the murderer’s remains were scattered among his victims—everything but the head, which came to rest on a delivery truck more than a hundred feet away, the bomber’s expression oddly serene.

The French interior minister arrived within ten minutes of the explosion. Seeing the carnage, he declared, “Baghdad has come to Paris.” Seventeen minutes later, it came to the Tivoli Gardens in Copenhagen, where, at 12:03 p.m., a second suicide bomber detonated himself amid a large group of children waiting impatiently to board the park’s roller coaster. The Danish security service, the PET, quickly established that the shahid had been born in Copenhagen, had attended Danish schools, and was married to a Danish woman. It seemed not to trouble him that his own children attended the same school as his victims.