The generator chugged loudly, and the farmhouse seemed brilliantly lit in the dark field, under a sky of stars.

They all crowded into the farmhouse. Elsie was sitting at her desk in the center, staring at them. Her eyes seemed distant.

"Elsie?"

"It's impossible," she said.

"What's impossible? What happened here?"

Marek looked over at David Stern, but he was still working at some analysis in the corner of the room.

Elsie sighed. "I don't know, I don't know…"

"Well," Marek said, "start at the beginning."

"Okay," she said. "The beginning." She stood up and crossed the room, where she pointed to a stack of parchments resting on a piece of plastic tarp on the floor. "This is the beginning. The document bundle I designated M-031, dug up from the monastery earlier today. David asked me to do it as soon as possible."

Nobody said anything. They just watched her.

"Okay," she said. "I've been going through the bundle. This is how I do it. I take about ten parchments at a time and bring them over here to my desk." She brought ten over. "Now, I sit down at the desk, and I go through them, one by one. Then, after I've summarized the contents of one sheet, and entered the summary into the computer, I take the sheet to be photographed, over here." She went to the next table, slipped a parchment under the camera.

Marek said, "We're familiar with-"

"No, you're not," she said sharply. "You're not familiar at all." Elsie went back to her table, took the next parchment off the stack. "Okay. So I go through them one by one. This particular stack consists of all kinds of documents: bills, copies of letters, replies to orders from the bishop, records of crop yields, lists of monastery assets. All dating from about the year 1357."

She took the parchments from the stack, one after the other.

"And then" - she removed the last one - "I see this."

They stared.

Nobody said anything.

The parchment was identical in size to the others in the stack, but instead of dense writing in Latin or Old French, this one had only two words, scrawled in plain English:

"In case you're wondering," she said, "that's the Professor's handwriting."

The room was silent. No one moved or shifted. They all just stared in complete silence.

Marek was thinking very fast, running through the possibilities. Because of his detailed, encyclopedic knowledge of the medieval period, for many years he had served as an outside consultant on medieval artifacts to the Metropolitan Museum of Art in New York. As a result, Marek had considerable experience with fakes of all kinds. It was true that he was rarely shown faked documents from the medieval period - the fakes were usually precious stones set in a bracelet that was ten years old, or a suit of armor that turned out to have been made in Brooklyn - but his experience had given him a clear way to think it through.

Marek said, "Okay. Begin at the beginning. Are you sure that's his handwriting?"

"Yes," Elsie said. "Without question."

"How do you know?"

She sniffed. "I'm a graphologist, Andre. But here. See for yourself."

She brought out a note that Johnston had scrawled a few days earlier, a note written in block letters, attached to a bill: "PLS CHK THIS CHARGE." She set it beside the parchment signature. "Block letters are actually easier to analyze. His H, for example, has a faint diagonal beneath. He draws one vertical line, lifts his pen, draws the second vertical, then drags his pen back to draw the crossbar, making the diagonal below. Or look at the P. He makes a downward stroke, then goes up and back to position to make the semicircle. Or the E, which he draws as an L and then zigzags back up to make the two added lines. There's no question. It's his handwriting."

"Someone couldn't have forged it?"

"No. Forgery, you have pen lifts and other signs. This writing is his."

Kate said, "Would he play a joke on us?"

"If he did, it isn't funny."

"What about this parchment it's written on?" Marek said. "Is it as old as the other sheets in the stack?"

"Yes," David Stern said, coming over. "Short of carbon dating, I'd say yes - it's the same age as the others."

Marek thought: How can that be? He said, "Are you sure? This parchment looks different. The surface looks rougher to me."

"It is rougher," Stern said. "Because it's been poorly scraped. Parchment was valuable material in medieval times. Generally it was used, scraped clean, and then used again. But if we look at this parchment under ultra-violet… Would somebody get the lights?" Kate turned them off, and in the darkness Stern swung a purple lamp over the table.

Marek immediately saw more writing, faint but clearly there on the parchment.

"This was originally a bill for lodging," Elsie said. "It's been scraped clean, quickly and crudely, as if somebody was in a hurry."

Chris said, "Are you saying the Professor scraped it?"

"I have no idea who scraped it. But it's not expertly done."

"All right," Marek said. "There's one definitive way to decide this, once and for all." He turned to Stern. "What about the ink, David? Is it genuine?"

Stern hesitated. "I'm not sure."

"Not sure? Why not?"

"Chemically speaking," Stern said, "it's exactly what you'd expect: iron in the form of ferrous oxide, mixed with gall as an organic binder. Some added carbon for blackness, and five percent sucrose. In those days, they used sugar to give the inks a shiny surface. So it's ordinary iron-gall ink, correct for the period. But that in itself doesn't mean much."

"Right." Stern was saying it could be faked.

"So I ran gall and iron titers," Stern said, "which I usually do in questionable cases. They tell us the exact amounts present in the ink. The titers indicate that this particular ink is similar but not identical to the ink on the other documents."

"Similar but not identical," Marek said. "How similar?"

"As you know, medieval inks were mixed by hand before use, because they didn't keep. Gall is organic - it's the ground-up nuts of an oak tree - which means the inks would eventually go bad. Sometimes they added wine to the ink as a preservative. Anyway, there's usually a fairly large variation in gall and iron content from one document to another. You find as much as twenty or thirty percent difference between documents. It's reliable enough that we can use these percentages to tell if two documents were written on the same day, from the same ink supply. This particular ink is about twenty-nine percent different from the documents on either side of it."

"Meaningless," Marek said. "Those numbers don't confirm either authenticity or forgery. Did you do a spectrographic analysis?"

"Yes. Just finished it. Here's the spectra for three documents, with the Professor's in the middle." Three lines, a series of spikes and dips. "Again, similar but not identical."

"Not that similar," Marek said, looking at the pattern of spikes. "Because along with the percentage difference in iron content, you've got lots of trace elements in the Professor's ink, including - what's this spike, for instance?"

"Chromium."

Marek sighed. "Which means it's modern."

"Not necessarily, no."

"There's no chromium in the inks before and after."

"That's true. But chromium is found in manuscript inks. Fairly commonly."

"Is there chromium in this valley?"

"No," Stern said, "but chromium was imported all over Europe, because it was used for fabric dyes as well as inks."

"But what about all these other contaminants?" Marek said, pointing to the other spikes. He shook his head. "I'm sorry. I'm just not buying this."