The security alarm on the west end of the Denon Wing sent the pigeons in the nearby TuileriesGardens scattering as Langdon and Sophie dashed out of the bulkhead into the Paris night. As theyran across the plaza to Sophie's car, Langdon could hear police sirens wailing in the distance.

　　"That's it there," Sophie called, pointing to a red snub-nosed two-seater parked on the plaza.

　　She's kidding, right? The vehicle was easily the smallest car Langdon had ever seen.

　　"SmartCar," she said. "A hundred kilometers to the liter."Langdon had barely thrown himself into the passenger seat before Sophie gunned the SmartCar upand over a curb onto a gravel divider. He gripped the dash as the car shot out across a sidewalk andbounced back down over into the small rotary at Carrousel du Louvre.

　　For an instant, Sophie seemed to consider taking the shortcut across the rotary by plowing straightahead, through the median's perimeter hedge, and bisecting the large circle of grass in the center.

　　"No!" Langdon shouted, knowing the hedges around Carrousel du Louvre were there to hide theperilous chasm in the center—La Pyramide Inversée—the upside-down pyramid skylight he hadseen earlier from inside the museum. It was large enough to swallow their Smart-Car in a singlegulp. Fortunately, Sophie decided on the more conventional route, jamming the wheel hard to theright, circling properly until she exited, cut left, and swung into the northbound lane, acceleratingtoward Rue de Rivoli.

　　The two-tone police sirens blared louder behind them, and Langdon could see the lights now in hisside view mirror. The SmartCar engine whined in protest as Sophie urged it faster away from theLouvre. Fifty yards ahead, the traffic light at Rivoli turned red. Sophie cursed under her breath andkept racing toward it. Langdon felt his muscles tighten.

　　"Sophie?"Slowing only slightly as they reached the intersection, Sophie flicked her headlights and stole aquick glance both ways before flooring the accelerator again and carving a sharp left turn throughthe empty intersection onto Rivoli. Accelerating west for a quarter of a mile, Sophie banked to theright around a wide rotary. Soon they were shooting out the other side onto the wide avenue ofChamps-Elysées.

　　As they straightened out, Langdon turned in his seat, craning his neck to look out the rear windowtoward the Louvre. The police did not seem to be chasing them. The sea of blue lights wasassembling at the museum.

　　His heartbeat finally slowing, Langdon turned back around. "That was interesting."Sophie didn't seem to hear. Her eyes remained fixed ahead down the long thoroughfare of Champs-Elysées, the two-mile stretch of posh storefronts that was often called the Fifth Avenue of Paris.

　　The embassy was only about a mile away, and Langdon settled into his seat. So dark the con ofman. Sophie's quick thinking had been impressive. Madonna of the Rocks.

　　Sophie had said her grandfather left her something behind the painting. A final message? Langdoncould not help but marvel over Saunière's brilliant hiding place; Madonna of the Rocks was yetanother fitting link in the evening's chain of interconnected symbolism. Saunière, it seemed, atevery turn, was reinforcing his fondness for the dark and mischievous side of Leonardo da Vinci.

　　Da Vinci's original commission for Madonna of the Rocks had come from an organization knownas the Confraternity of the Immaculate Conception, which needed a painting for the centerpiece ofan altar triptych in their church of San Francesco in Milan. The nuns gave Leonardo specificdimensions, and the desired theme for the painting—the Virgin Mary, baby John the Baptist, Uriel,and Baby Jesus sheltering in a cave. Although Da Vinci did as they requested, when he deliveredthe work, the group reacted with horror. He had filled the painting with explosive and disturbingdetails.

　　The painting showed a blue-robed Virgin Mary sitting with her arm around an infant child,presumably Baby Jesus. Opposite Mary sat Uriel, also with an infant, presumably baby John theBaptist. Oddly, though, rather than the usual Jesus-blessing-John scenario, it was baby John whowas blessing Jesus... and Jesus was submitting to his authority! More troubling still, Mary washolding one hand high above the head of infant John and making a decidedly threateninggesture—her fingers looking like eagle's talons, gripping an invisible head. Finally, the mostobvious and frightening image: Just below Mary's curled fingers, Uriel was making a cuttinggesture with his hand—as if slicing the neck of the invisible head gripped by Mary's claw-likehand.

　　Langdon's students were always amused to learn that Da Vinci eventually mollified theconfraternity by painting them a second, "watered-down" version of Madonna of the Rocks inwhich everyone was arranged in a more orthodox manner. The second version now hung inLondon's National Gallery under the name Virgin of the Rocks, although Langdon still preferredthe Louvre's more intriguing original.

　　As Sophie gunned the car up Champs-Elysées, Langdon said, "The painting. What was behind it?"Her eyes remained on the road. "I'll show you once we're safely inside the embassy.""You'll show it to me?" Langdon was surprised. "He left you a physical object?"Sophie gave a curt nod. "Embossed with a fleur-de-lis and the initials P.S."Langdon couldn't believe his ears.

　　We're going to make it, Sophie thought as she swung the SmartCar's wheel to the right, cuttingsharply past the luxurious H.tel de Crillon into Paris's tree-lined diplomatic neighborhood. Theembassy was less than a mile away now. She was finally feeling like she could breathe normallyagain.

　　Even as she drove, Sophie's mind remained locked on the key in her pocket, her memories ofseeing it many years ago, the gold head shaped as an equal-armed cross, the triangular shaft, theindentations, the embossed flowery seal, and the letters P.S.

　　Although the key barely had entered Sophie's thoughts through the years, her work in theintelligence community had taught her plenty about security, and now the key's peculiar tooling nolonger looked so mystifying. A laser-tooled varying matrix. Impossible to duplicate. Rather thanteeth that moved tumblers, this key's complex series of laser-burned pockmarks was examined byan electric eye. If the eye determined that the hexagonal pockmarks were correctly spaced,arranged, and rotated, then the lock would open.

　　Sophie could not begin to imagine what a key like this opened, but she sensed Robert would beable to tell her. After all, he had described the key's embossed seal without ever seeing it. Thecruciform on top implied the key belonged to some kind of Christian organization, and yet Sophieknew of no churches that used laser-tooled varying matrix keys.

　　Besides, my grandfather was no Christian....

　　Sophie had witnessed proof of that ten years ago. Ironically, it had been another key—a far morenormal one—that had revealed his true nature to her.

　　The afternoon had been warm when she landed at Charles de Gaulle Airport and hailed a taxihome. Grand-père will be so surprised to see me, she thought. Returning from graduate school inBritain for spring break a few days early, Sophie couldn't wait to see him and tell him all about theencryption methods she was studying.

　　When she arrived at their Paris home, however, her grandfather was not there. Disappointed, sheknew he had not been expecting her and was probably working at the Louvre. But it's Saturdayafternoon, she realize............