fragment, where a large shadow traced the contours of the stone.
Something caught Jonathan’s eye, and he crouched beside the case, inspecting not the fragments but the shadow beneath them. In the midst of the shadow, some of the halogen’s light appeared to break through to the floor, casting various lines. Jonathan stood up, and looking at the top of the map noticed that the concentric curves depicting the Colosseum allowed light to pass through the entire half-foot of marble to the floor.
Jonathan ducked again. The light illuminated vaguely formed Latin letters inside the stone’s shadow as though through a small projector.
He suddenly felt a long-dormant scholarly exhilaration, like what he had experienced during his graduate school days when after weeks of research a tattered papyrus became legible.
Jonathan now understood the words of the inscription, Tropaeum illumina. The imperative form. A command to “light ,” as in “to shine light on the stone.” The grammar on the underside of the fragment was not an accident. It was an instruction. Shine light on the stone.
He pushed the display case, wheeling it a few inches until it rested directly beneath the ceiling’s halogen light. With astonishing clarity, the light projected an uneven row of Latin letters illuminated against the stone’s shadow.
ERROR TITI
“Titus’s mistake,” Jonathan translated. He grabbed a pen and scribbled on an Alitalia napkin from his jacket pocket. “A steganographic message,” Jonathan said, referring to the ancient art of invisible writing.
He backed out of the room and hurried down a corridor lined with museum-quality Piranesi engravings. Jonathan could hear Mildren’s voice on a phone call and saw that one of the office doors was ajar. He knocked on the door and pushed it open. Mildren sat at his desk, speaking into a wireless headset. It was nearly two a.m. and Jonathan guessed it was the New York office on the other end, six hours behind European time. Does this guy ever sleep? Jonathan thought, waiting in the threshold.
“I’ll ring you back,” Mildren said, removing the small headset from his ear. “Yes?”
“Have we had an expert look at those fragments?” Jonathan asked.
“You’re the expert,” Mildren replied, leaning back in his office chair, arms crossed on his chest. “No others. Client’s instructions.”
“Because I think there is some kind of . . .” Jonathan paused. “Some kind of message engraved inside the stone.” He pointed toward the corridor. “I can show you if you’d—”
“Inside the stone,” Mildren said flatly. “A message inside the stone.”
“Carved inside, yes,” Jonathan said, handing Mildren the crumpled napkin where he drew a messy three-dimensional image of the marble fragment. “The top of the fragment depicts a location in Rome, just like other fragments of the Forma Urbis. But the carving of the Colosseum’s arena is deeper than it appears, allowing light to pass through the marble. On the reverse side someone chiseled cracks, which look natural, but really they filter light in the shape of letters. The halogen’s beam above the glass case projected onto the floor the words Error Titi, ‘Titus’s mistake.’”
“Titus’s mistake?” Mildren sat upright. “What the hell does that mean?”
“I think it’s a historical reference to a Roman emperor. According to ancient historians, Emperor Titus supposedly said on his deathbed: ‘I have made one mistake.’ ”
“What bloody mistake?” Mildren asked, losing his patience.
“One of the great unanswered questions of the ancient world,” Jonathan said with a shrug. “Before he was emperor, Titus led the Roman conquest of Jerusalem. Some historians say the mistake refers to his entering the Holy of Holies in the Temple, where no mortal was permitted.”
“Sounds a bit paranoid, no?”
“It would have, except when Titus later ascended the throne, an entire bustling Roman city was swallowed