Marek looked over her shoulder. "Very good, very good."

"Did they have oilcloth then?"

"Oh yes. Oilcloth is a Viking invention, perhaps ninth century. Quite common in Europe by our period. Although I don't think we have found anything else in the monastery that's wrapped in oilcloth."

He helped her dig. They proceeded cautiously, not wanting the mound to come down on them, but soon they had it exposed. It was a rectangle roughly two feet square, wrapped with oil-soaked string.

"I am guessing it's documents," Marek said. His fingers were twitching in the fluorescent light, he wanted to open it so badly, but he restrained himself. "We'll take it back with us."

He slipped it under his arm and headed back toward the entrance. She gave one last look at the earth mound, wondering if she had missed something. But she hadn't. She swung her light away and-

She stopped.

Out of the corner of her eye, she'd caught a glimpse of something shiny. She turned, looked again. For a moment, she couldn't find it, but then she did.

It was a small piece of glass, protruding from the earth.

"André?" she said. "I think there's more."

The glass was thin, and perfectly clear. The edge was curved and smooth, almost modern in its quality. She brushed the dirt away with her fingertips and exposed one lens of an eyeglass.

It was a bifocal lens.

"What is it?" André said, coming back to her.

"You tell me."

He squinted at it, shone his light very near. His face was so close to the glass, his nose almost touched it. "Where did you find this?" He sounded concerned.

"Right here."

"Lying in the open, just like now?" His voice was tense, almost accusing.

"No, only the edge was exposed. I cleaned it off."

"How?"

"With my finger."

"So: you are telling me it was partly buried?" He sounded like he didn't believe her.

"Hey, what is this?"

"Just answer, please."

"No, André. It was mostly buried. Everything but that left edge was buried."

"I wish you had not touched it."

"I do, too, if I'd known you were going to act like-"

"This must be explained," he said. "Turn around."

"What?"

"Turn around." He took her by the shoulder, turned her roughly, so she was facing away from him.

"Jesus." She glanced over her shoulder to see what he was doing. He held his light very close to her backpack and moved over the surface slowly, examining it minutely, then down to her shorts. "Uh, are you going to tell me-"

"Be quiet, please."

It was a full minute before he finished. "The lower left zip pocket of your pack is open. Did you open it?"

"No."

"Then it has been open all the time? Ever since you put the pack on?"

"I guess…"

"Did you brush against the wall at any time?"

"I don't think so." She had been careful about it, because she hadn't wanted the wall to break loose.

"Are you sure?" he said.

"For Christ's sake. No, André, I'm not sure."

"All right. Now you check me." He handed her his light, and turned his back to her.

"Check you how?" she said.

"That glass is contamination," he said. "We have to explain how it got here. Look to see if any part of my pack is open."

She looked. Nothing was.

"Did you look carefully?"

"Yes, I looked carefully," she said, annoyed.

"I think you didn't take enough time."

"André. I did."

Marek stared at the earthen mound in front of them. Small pebbles trickled down as he watched. "It could have fallen from one of our packs and then been covered…"

"Yes, I guess it could."

"If you could clean it with a fingertip, it was not tightly buried…"

"No, no. Very loose."

"All right. Then somehow, that is the explanation."

"What is?"

"Somehow, we brought this lens in with us, and while we were working on the oilskin documents, it fell from the pack, and was covered by dirt. Then you saw it, and cleaned it. It is the only explanation."

"Okay…"

He took out a camera, photographed the glass several times from different distances - very close, then progressively progressively farther back. Only then did he bring out a plastic baggie, lift the glass carefully with tweezers, and drop it into the bag. He brought out a small roll of bubble wrap, encased the bag, sealed it all with tape, and handed the bundle to her. "You bring it out. Please be careful." He seemed more relaxed. He was being nicer to her.

"Okay," she said. They climbed the dirt slope again, heading back outside.

They were greeted by cheers from the undergraduates, and the oilskin package was handed over to Elsie, who quickly took it back to the farmhouse. Everyone was laughing and smiling, except Chang and Chris Hughes. They were wearing headsets, and had heard everything inside the cave. They looked gloomy and upset.

Site contamination was extremely serious, and they all knew it. Because it implied sloppy excavation technique, it called into question any other, legitimate discoveries made by the team. A typical instance was a minor scandal at Les Eyzies the year before.

Les Eyzies was a Paleolithic site, a habitation of early man beneath a cliff ledge. The archaeologists had been digging at a level that dated to 320,000 B.P., when one of them found a half-buried condom. It was still in its metallic wrapper, and nobody thought for a moment that it belonged at that level. But the fact that it had been found there - half-buried - suggested that they were not being careful in their technique. It caused a near panic among the team, which persisted even after a graduate student was sent back to Paris in disgrace.

"Where is this glass lens?" Chris said to Marek.

"Kate has it."

She gave it to Chris. While everyone else was cheering, he turned away, unwrapped the package, and held the baggie up to the light.

"Definitely modern," he said. He shook his head unhappily. "I'll check it out. Just make sure you include it in the site report."

Marek said he would.

Then Rick Chang turned away and clapped his hands. "All right, everybody. Excitement's over. Back to work!"

In the afternoon, Marek scheduled archery practice. The undergraduates were amused by it, and they never missed a session; recently Kate had taken it up, as well. The target today was a straw-filled scarecrow, set about fifty yards away. The kids were all lined up, holding their bows, and Marek strode down behind them.

"To kill a man," he said, "you have to remember: he is almost certainly wearing plate armor on his chest. He's less likely to have armor on his head and neck, or on his legs. So to kill him, you must shoot him in the head, or on the side of his torso, where the plates don't cover."

Kate listened to Marek, amused. André took everything so seriously. To kill a man. As if he really meant it. Standing in the yellow afternoon sunlight of southern France, hearing the distant honk of cars on the road, the idea seemed slightly absurd.

"But if you want to stop a man," Marek continued, "then shoot him in the leg. He'll go right down. Today we'll use the fifty-pound bows."

Fifty pounds referred to the draw weight, what was needed to pull the string back. The bows were certainly heavy, and difficult to draw. The arrows were almost three feet long. Many of the kids had trouble with it, especially at first. Marek usually finished each practice session with some weight lifting, to build up their muscles.

Marek himself could draw a hundred-pound bow. Although it was difficult to believe, he insisted that this was the size of actual fourteenth-century weapons - far beyond what any of them could use.

"All right," Marek said, "nock your arrows, aim, and loose them, please." Arrows flew through the air. "No, no, no, David, don't pull until you tremble. Maintain control. Carl, look at your stance. Bob, too high. Deanna, remember your fingers. Rick, that was much better. All right, here we go again, nock your arrows, aim, and… loose them!"