In the aftermath of al-Qaeda’s attacks on the World Trade Center and the Pentagon, the government of France devised a four-tiered color-coded system similar to that of the United States. On that afternoon the level stood at Orange, the second level, with only Yellow being lower. The third level, Red, would automatically close vast stretches of French airspace and put in place additional security precautions in the transit systems and at French landmarks such as the Louvre and the Eiffel Tower. The highest level, Scarlet, would virtually shut down the country, including its water supply and power grid. No member of Group Napoleon was prepared to do that based on a warning from the Israelis. “The target of the attack is likely to be Israeli or Jewish in nature,” said the interior minister. “Even if it’s on the scale of Rome, it doesn’t justify increasing the level to Scarlet.”

“I concur,” the president said. “We’ll raise it to Red.”

Five minutes later, when the meeting of Group Napoleon adjourned, the French interior minister strode out of the Salon Murat to face the cameras and the microphones. “Ladies and gentlemen,” he began, his facial expression grave, “the government of France has received what it believes is credible evidence of a pending terrorist attack against Paris this evening. . . .”

THE APARTMENT HOUSE was on the rue de Saules, in the quiet northern end of Montmartre, several streets away from the tourist morass around Sacré-Coeur. The flat was small but comfortable, a perfect pied-à-terre for those occasions when work or romantic pursuits brought Paul Martineau from Provence to the capital. After arriving in Paris, he’d gone to the Luxembourg Quarter to have lunch with a colleague from the Sorbonne. Then it was over to St-Germain for a meeting with a prospective publisher for his book on the pre-Roman history of ancient Provence. At 4:45 he was strolling across the quiet courtyard of the building and letting himself into the foyer. Madame Touzet, the concierge, poked her head out of her door as Martineau came inside.

“Bonjour, Professor Martineau.”

Martineau kissed her powdered cheeks and presented her with a bunch of lilies he’d bought from a stall on the rue Caulaincourt. Martineau never came to his Paris flat without bringing a small treat for Madame Touzet.

“For me?” she asked elaborately. “You shouldn’t have, Professor.”

“I couldn’t help myself.”

“How long are you in Paris?”

“Only for one night.”

“A tragedy! I’ll get your mail.”