〃Actually；〃 Langdon replied； feeling a tingle of excitement ripple through him； 〃the keystone is believed to have been created by the Priory sometime in the past couple of decades。〃
Sophie's eyes flashed disbelief。 〃But if this cryptex reveals the hiding place of the Holy Grail； why would my grandfather give it to me？ I have no idea how to open it or what to do with it。 I don't even know what the Holy Grail is！〃
Langdon realized to his surprise that she was right。 He had not yet had a chance to explain to Sophie the true nature of the Holy Grail。 That story would have to wait。 At the moment； they were focused on the keystone。
If that is indeed what this is。。。。
Against the hum of the bulletproof wheels beneath them； Langdon quickly explained to Sophie everything he had heard about the keystone。 Allegedly； for centuries； the Priory's biggest secret—the location of the Holy Grail—was never written down。 For security's sake； it was verbally transferred to each new rising sénéchal at a clandestine ceremony。 However； at some point during the last century； whisperings began to surface that the Priory policy had changed。 Perhaps it was on account of new electronic eavesdropping capabilities； but the Priory vowed never again even to speak the location of the sacred hiding place。
〃But then how could they pass on the secret？〃 Sophie asked。
〃That's where the keystone es in；〃 Langdon explained。 〃When one of the top four members died； the remaining three would choose from the lower echelons the next candidate to ascend as sénéchal。 Rather than telling the new sénéchal where the Grail was hidden； they gave him a test through which he could prove he was worthy。〃
Sophie looked unsettled by this； and Langdon suddenly recalled her mentioning how her grandfather used to make treasure hunts for her—preuves de mérite。 Admittedly； the keystone was a similar concept。 Then again； tests like this were extremely mon in secret societies。 The best known was the Masons'； wherein members ascended to higher degrees by proving they could keep a secret and by performing rituals and various tests of merit over many years。 The tasks became progressively harder until they culminated in a successful candidate's induction as thirty…second…degree Mason。
〃So the keystone is a preuve de mérite；〃 Sophie said。 〃If a rising Priory sénéchal can open it； he proves himself worthy of the information it holds。〃
Langdon nodded。 〃I forgot you'd had experience with this sort of thing。〃
〃Not only with my grandfather。 In cryptology； that's called a 'self…authorizing language。' That is； if you're smart enough to read it； you're permitted to know what is being said。〃
Langdon hesitated a moment。 〃Sophie； you realize that if this is indeed the keystone； your grandfather's access to it implies he was exceptionally powerful within the Priory of Sion。 He would have to have been one of the highest four members。〃
Sophie sighed。 〃He was powerful in a secret society。 I'm certain of it。 I can only assume it was the Priory。〃
Langdon did a double take。 〃You knew he was in a secret society？〃
〃I saw some things I wasn't supposed to see ten years ago。 We haven't spoken since。〃 She paused。 〃My grandfather was not only a ranking top member of the group。。。 I believe he was the top member。〃
Langdon could not believe what she had just said。 〃Grand Master？ But。。。 there's no way you could know that！〃
〃I'd rather not talk about it。〃 Sophie looked away； her expression as determined as it was pained。
Langdon sat in stunned silence。 Jacques Saunière？ Grand Master？ Despite the astonishing repercussions if it were true； Langdon had the eerie sensation it almost made perfect sense。 After all； previous Priory Grand Masters had also been distinguished public figures with artistic souls。 Proof of that fact had been uncovered years ago in Paris's Bibliothèque Nationale in papers that became known as Les Dossiers Secrets。
Every Priory historian and Grail buff had read the Dossiers。 Cataloged under Number 4° lm1 249； the Dossiers Secrets had been authenticated by many specialists and incontrovertibly confirmed what historians had suspected for a long time： Priory Grand Masters included Leonardo da Vinci； Botticelli； Sir Isaac Newton； Victor Hugo； and； more recently； Jean Cocteau； the famous Parisian artist。
Why not Jacques Saunière？
Langdon's incredulity intensified with the realization that he had been slated to meet Saunière tonight。 The Priory Grand Master called a meeting with me。 Why？ To make artistic small talk？ It suddenly seemed unlikely。 After all； if Langdon's instincts were correct； the Grand Master of the Priory of Sion had just transferred the brotherhood's legendary keystone to his granddaughter and simultaneously manded her to find Robert Langdon。
Inconceivable！
Langdon's imagination could conjure no set of circumstances that would explain Saunière's behavior。 Even if Saunière feared his own death； there were three sénéchaux who also possessed the secret and therefore guaranteed the Priory's security。 Why would Saunière take such an enormous risk giving his granddaughter the keystone； especially when the two of them didn't get along？ And why involve Langdon。。。 a total stranger？
A piece of this puzzle is missing； Langdon thought。
The answers were apparently going to have to wait。 The sound of the slowing engine caused them both to look up。 Gravel crunched beneath the tires。 Why is he pulling over already？ Langdon wondered。 Vernet had told them he would take them well outside the city to safety。 The truck decelerated to a crawl and made its way over unexpectedly rough terrain。 Sophie shot Langdon an uneasy look； hastily closing the cryptex box and latching it。 Langdon slipped his jacket back on。
When the truck came to a stop； the engine remained idling as the locks on the rear doors began to turn。 When the doors swung open； Langdon was surprised to see they were parked in a wooded area； well off the road。 Vernet stepped into view； a strained look in his eye。 In his hand； he held a pistol。
〃I'm sorry about this；〃 he said。 〃I really have no choice。〃
CHAPTER 49
André Vernet looked awkward with a pistol； but his eyes shone with a determination that Langdon sensed would be unwise to test。
〃I'm afraid I must insist；〃 Vernet said； training the weapon on the two of them in the back of the idling truck。 〃Set the box down。〃
Sophie clutched the box to her chest。 〃You said you and my grandfather were friends。〃
〃I have a duty to protect your grandfather's assets；〃 Vernet replied。 〃And that is exactly what I am doing。 Now set the box on the floor。〃
〃My grandfather entrusted this to me！〃 Sophie declared。
〃Do it；〃 Vernet manded； raising the gun。
Sophie set the box at her feet。
Langdon watched the gun barrel swing now in his direction。
〃Mr。 Langdon；〃 Vernet said； 〃you will bring the box over to me。 And be aware that I'm asking you because you I would not hesitate to shoot。〃
Langdon stared at the banker in disbelief。 〃Why are you doing this？〃
〃Why do you imagine？〃 Vernet snapped； his accented English terse now。 〃To protect my client's assets。〃
〃We are your clients now；〃 Sophie said。
Vernet's visage turned ice…cold； an eerie transformation。 〃Mademoiselle Neveu； I don't know how you got that key and account number tonight； but it seems obvious that foul play was involved。 Had I known the extent of your crimes； I would never have helped you leave the bank。〃
〃I told you；〃 Sophie said； 〃we had nothing to do with my grandfather's death！〃
Vernet looked at Langdon。 〃And yet the radio claims you are wanted not only for the murder of Jacques Saunière but for those of three other men as well？〃
〃What！〃 Langdon was thunderstruck。 Three more murders？ The coincidental number hit him harder than the fact that he was the prime suspect。 It seemed too unlikely to be a coincidence。 The three sénéchaux？ Langdon's eyes dropped to the rosewood box。 If the sénéchaux were murdered； Saunière had no options。 He had to transfer the keystone to someone。
〃The police can sort that out when I turn you in；〃 Vernet said。 〃I have gotten my bank involved too far already。〃
Sophie glared at Vernet。 〃You obviously have no intention of turning us in。 You would have driven us back to the bank。 And instead you bring us out here and hold us at gunpoint？〃
〃Your grandfather hired me for one reason—to keep his possessions both safe and private。 Whatever this box contains； I have no intention of letting it bee a piece of cataloged evidence in a police investigation。 Mr。 Langdon； bring me the box。〃
Sophie shook her head。 〃Don't do it。〃
A gunshot roared； and a bullet tore into the wall above him。 The reverberation shook the back of the truck as a spent shell clinked onto the cargo floor。
Shit！ Langdon froze。
Vernet spoke more confidently now。 〃Mr。 Langdon； pick up the box。〃
Langdon lifted the box。
〃Now bring it over to me。〃 Vernet was taking dead aim； standing on the ground behind the rear bumper； his gun outstretched into the cargo hold now。
Box in hand； Langdon moved across the hold toward the open door。
I've got to do something！ Langdon thought。 I'm about to hand over the Priory keystone！ As Langdon moved toward the doorway； his position of higher ground became more pronounced； and he began