Struggling with the gear shift, Langdon managed to maneuver the hijacked taxi to the far side ofthe Bois de Boulogne while stalling only twice. Unfortunately, the inherent humor in the situationwas overshadowed by the taxi dispatcher repeatedly hailing their cab over the radio.

　　"Voiture cinq-six-trois. Où êtes-vous? Répondez!"When Langdon reached the exit of the park, he swallowed his machismo and jammed on thebrakes. "You'd better drive."Sophie looked relieved as she jumped behind the wheel. Within seconds she had the car hummingsmoothly westward along Allée de Longchamp, leaving the Garden of Earthly Delights behind.

　　"Which way is Rue Haxo?" Langdon asked, watching Sophie edge the speedometer over a hundredkilometers an hour.

　　Sophie's eyes remained focused on the road. "The cab driver said it's adjacent to the Roland Garrostennis stadium. I know that area."Langdon pulled the heavy key from his pocket again, feeling the weight in his palm. He sensed itwas an object of enormous consequence. Quite possibly the key to his own freedom.

　　Earlier, while telling Sophie about the Knights Templar, Langdon had realized that this key, inaddition to having the Priory seal embossed on it, possessed a more subtle tie to the Priory of Sion.

　　The equal-armed cruciform was symbolic of balance and harmony but also of the Knights Templar.

　　Everyone had seen the paintings of Knights Templar wearing white tunics emblazoned with redequal-armed crosses. Granted, the arms of the Templar cross were slightly flared at the ends, butthey were still of equal length.

　　A square cross. Just like the one on this key.

　　Langdon felt his imagination starting to run wild as he fantasized about what they might find. TheHoly Grail. He almost laughed out loud at the absurdity of it. The Grail was believed to besomewhere in England, buried in a hidden chamber beneath one of the many Templar churches,where it had been hidden since at least 1500.

　　The era of Grand Master Da Vinci.

　　The Priory, in order to keep their powerful documents safe, had been forced to move them manytimes in the early centuries. Historians now suspected as many as six different Grail relocationssince its arrival in Europe from Jerusalem. The last Grail "sighting" had been in 1447 whennumerous eyewitnesses described a fire that had broken out and almost engulfed the documentsbefore they were carried to safety in four huge chests that each required six men to carry. Afterthat, nobody claimed to see the Grail ever again. All that remained were occasional whisperingsthat it was hidden in Great Britain, the land of King Arthur and the Knights of the Round Table.

　　Wherever it was, two important facts remained:

　　Leonardo knew where the Grail resided during his lifetime.

　　That hiding place had probably not changed to this day.

　　For this reason, Grail enthusiasts still pored over Da Vinci's art and diaries in hopes of unearthing ahidden clue as to the Grail's current location. Some claimed the mountainous backdrop in Madonnaof the Rocks matched the topography of a series of cave-ridden hills in Scotland. Others insistedthat the suspicious placement of disciples in The Last Supper was some kind of code. Still othersclaimed that X rays of the Mona Lisa revealed she originally had been painted wearing a lapislazuli pendant of Isis—a detail Da Vinci purportedly later decided to paint over. Langdon hadnever seen any evidence of the pendant, nor could he imagine how it could possibly reveal theHoly Grail, and yet Grail aficionados still discussed it ad nauseum on Internet bulletin boards andworldwide-web chat rooms.

　　Everyone loves a conspiracy.

　　And the conspiracies kept coming. Most recently, of course, had been the earthshaking discoverythat Da Vinci's famed Adoration of the Magi was hiding a dark secret beneath its layers of paint.

　　Italian art diagnostician Maurizio Seracini had unveiled the unsettling truth, which the New YorkTimes Magazine carried prominently in a story titled "The Leonardo Cover-Up."Seracini had revealed beyond any doubt that while the Adoration's gray-green sketchedunderdrawing was indeed Da Vinci's work, the painting itself was not. The truth was that someanonymous painter had filled in Da Vinci's sketch like a paint-by-numbers years after Da Vinci'sdeath. Far more troubling, however, was what lay beneath the impostor's paint. Photographs takenwith infrared reflectography and X ray suggested that this rogue painter, while filling in Da Vinci'ssketched study, had made suspicious departures from the underdrawing... as if to subvert DaVinci's true intention. Whatever the true nature of the underdrawin............