The inside of Gare Saint-Lazare looked like every other train station in Europe, a gaping indoor-outdoor cavern dotted with the usual suspects—homeless men holding cardboard signs, collectionsof bleary-eyed college kids sleeping on backpacks and zoning out to their portable MP3 players,and clusters of blue-clad baggage porters smoking cigarettes.

　　Sophie raised her eyes to the enormous departure board overhead. The black and white tabsreshuffled, ruffling downward as the information refreshed. When the update was finished,Langdon eyed the offerings. The topmost listing read: LYON—RAPIDE—3:06"I wish it left sooner," Sophie said, "but Lyon will have to do." Sooner? Langdon checked hiswatch 2:59 A.M. The train left in seven minutes and they didn't even have tickets yet.

　　Sophie guided Langdon toward the ticket window and said, "Buy us two tickets with your creditcard.""I thought credit card usage could be traced by—""Exactly."Langdon decided to stop trying to keep ahead of Sophie Neveu. Using his Visa card, he purchasedtwo coach tickets to Lyon and handed them to Sophie.

　　Sophie guided him out toward the tracks, where a familiar tone chimed overhead and a P.A.

　　announcer gave the final boarding call for Lyon. Sixteen separate tracks spread out before them. Inthe distance to the right, at quay three, the train to Lyon was belching and wheezing in preparationfor departure, but Sophie already had her arm through Langdon's and was guiding him in the exactopposite direction. They hurried through a side lobby, past an all-night cafe, and finally out a sidedoor onto a quiet street on the west side of the station.

　　A lone taxi sat idling by the doorway.

　　The driver saw Sophie and flicked his lights.

　　Sophie jumped in the back seat. Langdon got in after her.

　　As the taxi pulled away from station, Sophie took out their newly purchased train tickets and torethem up.

　　Langdon sighed. Seventy dollars well spent.

　　It was not until their taxi had settled into a monotonous northbound hum on Rue de Clichy thatLangdon felt they'd actually escaped. Out the window to his right, he could see Montmartre and thebeautiful dome of Sacré-Coeur. The image was interrupted by the flash of police lights sailing pastthem in the opposite direction.

　　Langdon and Sophie ducked down as the sirens faded.

　　Sophie had told the cab driver simply to head out of the city, and from her firmly set jaw, Langdonsensed she was trying to figure out their next move.

　　Langdon examined the cruciform key again, holding it to the window, bringing it close to his eyesin an effort to find any markings on it that might indicate where the key had been made. In theintermittent glow of passing streetlights, he saw no markings except th............