obert Langdon felt light-headed as he trudged toward the end of the Grand Gallery. Sophie's phone message played over and over in his mind. At the end of the corridor, illuminated signs bearing the international stick-figure symbols for rest rooms guided him through a maze-like series of dividers displaying Italian drawings and hiding the rest rooms from sight.

Finding the men's room door, Langdon entered and turned on the lights.

The room was empty.

Walking to the sink, he splashed cold water on his face and tried to wake up. Harsh fluorescent lights glared off the stark tile, and the room smelled of ammonia. As he toweled off, the rest room's door creaked open behind him. He spun.

Sophie Neveu entered, her green eyes flashing fear. "Thank God you came. We don't have much time."

Langdon stood beside the sinks, staring in bewilderment at DCPJ cryptographer Sophie Neveu. Only minutes ago, Langdon had listened to her phone message, thinking the newly arrived cryptographer must be insane. And yet, the more he listened, the more he sensed Sophie Neveu was speaking in earnest. Do not react to this message. Just listen calmly. You are in danger right now. Follow my directions very closely. Filled with uncertainty, Langdon had decided to do exactly as Sophie advised. He told Fache that the phone message was regarding an injured friend back home. Then he had asked to use the rest room at the end of the Grand Gallery.

Sophie stood before him now, still catching her breath after doubling back to the rest room. In the fluorescent lights, Langdon was surprised to see that her strong air actually radiated from unexpectedly soft features. Only her gaze was sharp, and the juxtaposition conjured images of a multilayered Renoir portrait… veiled but distinct, with a boldness that somehow retained its shroud of mystery.

"I wanted to warn you, Mr. Langdon…" Sophie began, still catching her breath, "that you are sous surveillance cachée. Under a guarded observation." As she spoke, her accented English resonated off the tile walls, giving her voice a hollow quality.

"But… why?" Langdon demanded. Sophie had already given him an explanation on the phone, but he wanted to hear it from her lips.

"Because," she said, stepping toward him, "Fache's primary suspect in this murder is you."

Langdon was braced for the words, and yet they still sounded utterly ridiculous. According to Sophie, Langdon had been called to the Louvre tonight not as a symbologist but rather as a suspect and was currently the unwitting target of one of DCPJ's favorite interrogation methods—surveillance cachée—a deft deception in which the police calmly invited a suspect to a crime scene and interviewed him in hopes he would get nervous and mistakenly incriminate himself.

"Look in your jacket's left pocket," Sophie said. "You'll find proof they are watching you."

Langdon felt his apprehension rising. Look in my pocket? It sounded like some kind of cheap magic trick.

"Just look."

Bewildered, Langdon reached his hand into his tweed jacket's left pocket—one he never used. Feeling around inside, he found nothing. What the devil did you expect? He began wondering if Sophie might just be insane after all. Then his fingers brushed something unexpected. Small and hard. Pinching the tiny object between his fingers, Langdon pulled it out and stared in astonishment. It was a metallic, button-shaped disk, about the size of a watch battery. He had never seen it before. "What the…?"

"GPS tracking dot," Sophie said. "Continuously transmits its location to a Global Positioning System satellite that DCPJ can monitor. We use them to monitor people's locations. It's accurate within two feet anywhere on the globe. They have you on an electronic leash. The agent who picked you up at the hotel slipped it inside your pocket before you left your room."

Langdon flashed back to the hotel room… his quick shower, getting dressed, the DCPJ agent politely holding out Langdon's tweed coat as they left the room. It's cool outside, Mr. Langdon, the agent had said. Spring in Paris is not all your song boasts. Langdon had thanked him and donned the jacket.

Sophie's olive gaze was keen. "I didn't tell you about the tracking dot earlier because I didn't want you checking your pocket in front of Fache. He can't know you've found it."

Langdon had no idea how to respond.

"They tagged you with GPS because they thought you might run." She paused. "In fact, they hoped you would run; it would make their case stronger."

"Why would I run!" Langdon demanded. "I'm innocent!"

"Fache feels otherwise."

Angrily, Langdon stalked toward the trash receptacle to dispose of the tracking dot.

"No!" Sophie grabbed his arm and stopped him. "Leave it in your pocket. If you throw it out, the signal will stop moving, and they'll know you found the dot. The only reason Fache left you alone is because he can monitor where you are. If he thinks you've discovered what he's doing…" Sophie did not finish the thought. Instead, she pried the metallic disk from Langdon's hand and slid it back into the pocket of his tweed coat. "The dot stays with you. At least for the moment."

Langdon felt lost. "How the hell could Fache actually believe I killed Jacques Saunière!"

"He has some fairly persuasive reasons to suspect you." Sophie's expression was grim. "There is a piece of evidence here that you have not yet seen. Fache has kept it carefully hidden from you."

Langdon could only stare.

"Do you recall the three lines of text that Saunière wrote on the floor?"

Langdon nodded. The numbers and words were imprinted on Langdon's mind.

Sophie's voice dropped to a whisper now. "Unfortunately, what you saw was not the entire message. There was a fourth line that Fache photographed and then wiped clean before you arrived."

Although Langdon knew the soluble ink of a watermark stylus could easily be wiped away, he could not imagine why Fache would erase evidence.

"The last line of the message," Sophie said, "was something Fache did not want you to know about." She paused. "At least not until he was done with you."

Sophie produced a computer printout of a photo from her sweater pocket and began unfolding it. "Fache uploaded images of the crime scene to the Cryptology Department earlier tonight in hopes we could figure out what Saunière's message was trying to say. This is a photo of the complete message." She handed the page to Langdon.

Bewildered, Langdon looked at the image. The close-up photo revealed the glowing message on the parquet floor. The final line hit Langdon like a kick in the gut.

13-3-2-21-1-1-8-5

O, Draconian devil!

Oh, lame saint!

P.S. Find Robert Langdon