«I know, sweetie. You’re forgiven. I can’t possibly stay mad at you. Grandfathers and granddaughters always forgive each other.»

Sophie knew she shouldn’t ask, but she couldn’t help it. «What does it open? I never saw a key like that. It was very pretty.»

Her grandfather was silent a long moment, and Sophie could see he was uncertain how to answer.

Grand-père never lies. «It opens a box,» he finally said. «Where I keep many secrets.» Sophie pouted. «I hate secrets!» «I know, but these are important secrets. And someday, you’ll learn to appreciate them as much as I do.»

«I saw letters on the key, and a flower.»

«Yes, that’s my favorite flower. It’s called a fleur-de-lis. We have them in the garden. The white ones. In English we call that kind of flower a lily.»

«I know those! They’re my favorite too!»

«Then I’ll make a deal with you.» Her grandfather’s eyebrows raised the way they always did when he was about to give her a challenge. «If you can keep my key a secret, and never talk about it ever again, to me or anybody, then someday I will give it to you.»

Sophie couldn’t believe her ears. «You will?»

«I promise. When the time comes, the key will be yours. It has your name on it.» Sophie scowled. «No it doesn’t. It said P. S. My name isn’t P. S. !» Her grandfather lowered his voice and looked around as if to make sure no one was listening. «Okay, Sophie, if you must know, P. S. is a code. It’s your secret initials.»

Her eyes went wide. «I have secret initials?»

«Of course. Granddaughters always have secret initials that only their grandfathers know.» «P. S. ?» He tickled her. «Princesse Sophie.»

She giggled. «I’m not a princess!» He winked. «You are to me.» From that day on, they never again spoke of the key. And she became his Princess Sophie.

Inside the Salle des Etats, Sophie stood in silence and endured the sharp pang of loss. «The initials,» Langdon whispered, eyeing her strangely. «Have you seen them?» Sophie sensed her grandfather’s voice whispering in the corridors of the museum. Never speak ofthis key, Sophie.To me or to anyone.She knew she had failed him in forgiveness, and she wondered if she could break his trust again. P. S. Find Robert Langdon.Her grandfather wanted Langdon to help. Sophie nodded. «Yes, I saw the initials P. S. once. When I was very young.»

«Where?»

Sophie hesitated. «On something very important to him.»

Langdon locked eyes with her. «Sophie, this is crucial. Can you tell me if the initials appeared with a symbol? A fleur-de-lis?» Sophie felt herself staggering backward in amazement. «But… how could you possibly know that!» Langdon exhaled and lowered his voice. «I’m fairly certain your grandfather was a member of a secret society. A very old covert brotherhood.»

Sophie felt a knot tighten in her stomach. She was certain of it too. For ten years she had tried to forget the incident that had confirmed that horrifying fact for her. She had witnessed something unthinkable. Unforgivable.

«The fleur-de-lis,» Langdon said,» combined with the initials P. S. , that is the brotherhood’s official device. Their coat of arms. Their logo.»

«How do you know this?» Sophie was praying Langdon was not going to tell her that he himselfwas a member.

«I’ve written about this group,» he said, his voice tremulous with excitement. «Researching the symbols of secret societies is a specialty of mine. They call themselves the Prieuré de Sion – the Priory of Sion. They’re based here in France and attract powerful members from all over Europe. In fact, they are one of the oldest surviving secret societies on earth.»

Sophie had never heard of them.

Langdon was talking in rapid bursts now. «The Priory’s membership has included some of history’s most cultured individuals: men like Botticelli, Sir Isaac Newton, Victor Hugo.» He paused, his voice brimming now with academic zeal. «And, Leonardo Da Vinci.» Sophie stared. «Da Vinci was in a secret society?»

«Da Vinci presided over the Priory between 1510 and 1519 as the brotherhood’s Grand Master, which might help explain your grandfather’s passion for Leonardo’s work. The two men share a historical fraternal bond. And it all fits perfectly with their fascination for goddess iconology, paganism, feminine deities, and contempt for the Church. The Priory has a well-documented history of reverence for the sacred feminine.»

«You’re telling me this group is a pagan goddess worship cult?»

«More like the pagan goddess worship cult. But more important, they are known as the guardians of an ancient secret. One that made them immeasurably powerful.»

Despite the total conviction in Langdon’s eyes, Sophie’s gut reaction was one of stark disbelief. Asecret pagan cult? Once headed by Leonardo Da Vinci? It all sounded utterly absurd. And yet, even as she dismissed it, she felt her mind reeling back ten years – to the night she had mistakenly surprised her grandfather and witnessed what she still could not accept. Could that explain – ?

«The identities of living Priory members are kept extremely secret,» Langdon said,» but the P. S. and fleur-de-lis that you saw as a child are proof. It could only have been related to the Priory.»

Sophie realized now that Langdon knew far more about her grandfather than she had previously imagined. This American obviously had volumes to share with her, but this was not the place. «I can’t afford to let them catch you, Robert. There’s a lot we need to discuss. You need to go!»

Langdon heard only the faint murmur of her voice. He wasn’t going anywhere. He was lost in another place now. A place where ancient secrets rose to the surface. A place where forgotten histories emerged from the shadows.

Slowly, as if moving underwater, Langdon turned his head and gazed through the reddish haze toward the Mona Lisa.

The fleur-de-lis… the flower of Lisa… the Mona Lisa.

It was all intertwined, a silent symphony echoing the deepest secrets of the Priory of Sion and Leonardo Da Vinci.

A few miles away, on the riverbank beyond Les Invalides, the bewildered driver of a twin-bed Trailor truck stood at gunpoint and watched as the captain of the Judicial Police let out a guttural roar of rage and heaved a bar of soap out into the turgid waters of the Seine.

Silas gazed upward at the Saint-Sulpice obelisk, taking in the length of the massive marble shaft. His sinews felt taut with exhilaration. He glanced around the church one more time to make sure he was alone. Then he knelt at the base of the structure, not out of reverence, but out of necessity.

The keystone is hidden beneath the Rose Line. At the base of the Sulpice obelisk. All the brothers had concurred.

On his knees now, Silas ran his hands across the stone floor. He saw no cracks or markings to indicate a movable tile, so he began rapping softly with his knuckles on the floor. Following the brass line closer to the obelisk, he knocked on each tile adjacent to the brass line. Finally, one of them echoed strangely.

There’s a hollow area beneath the floor!

Silas smiled. His victims had spoken the truth.

Standing, he searched the sanctuary for something with which to break the floor tile.

High above Silas, in the balcony, Sister Sandrine stifled a gasp. Her darkest fears had just been confirmed. This visitor was not who he seemed. The mysterious Opus Dei monk had come to Saint- Sulpice for another purpose.

A secret purpose.

You are not the only one with secrets, she thought.

Sister Sandrine Bieil was more than the keeper of this church. She was a sentry. And tonight, the ancient wheels had been set in motion. The arrival of this stranger at the base of the obelisk was a signal from the brotherhood.