'But Lascaux was discovered in the nineteen forties,' Fulano said. 'As far as historians believe, Altamira – three hundred kilometers west of here – was the first to be explored. In eighteen seventy-nine. But my ancestor discovered these paintings ten years before. He knew instinctively that no expert in pre-history would believe in their authenticity. How could primitive human beings have produced such exquisite beauty? Scholars would conclude that these brilliant paintings were recent, cleverly forged. To prevent his discovery from being ridiculed, he kept it to himself, placing a door across the cave, preserving it for himself, his family, and special friends. His instincts served him well, for when Altamira was discovered, the experts scoffed. Only when other caves with paintings were discovered in France did anthropologists admit their mistake and accept the images at Altamira as authentic. Lascaux and Altamira are so impressive that they're often referred to as the Sistine Chapels of paleolithic art. But I've seen Lascaux, and I've seen Altamira, and I tell you that they can't compare to what you've been privileged to witness. This is the true Sistine Chapel of paleolithic art. My ancestor was wise in another respect as well. He understood that this cave, after tens of thousands of years of not being disturbed, was so delicate that if people flocked to see these images, the warmth from their bodies would affect its ecology. The soil on their shoes would leave contaminants. The breath from their mouths would add to the humidity on the walls. These paintings, preserved by a blessed accident of nature, would be destroyed by fungus and the soot from torches. Only a few special witnesses could ever be allowed inside. The twentieth century proves that he was correct. So many tourists entered Lascaux that the paintings became covered with destructive green mold. The cave had to be sealed again, only experts allowed to enter and even then only after special precautions were taken, for example a disinfecting pool through which the limited observers had to step in order to kill the contaminants on their shoes. At Altamira, only a few can enter each day, and only then by appointment. But here, in this isolated cave in this isolated valley, even fewer are allowed to enter. The double doors provide an extra buffer, a way of keeping the outside air filled with pollen and seeds from entering the inner chamber. You were told that this would be the greatest memory of your lives. I assure you that, after a hundred years and more, your memories are shared by a precious minority.'

'And you haven't even seen the best part,' Gerrard said.

'There are other paintings?' Craig raised his eyebrows in amazement.

'Yes, one more chamber,' Fulano said, his dark eyes gleaming. 'The best for last. Come. Appreciate. Worship.'

'Believe me, I already have.'

'Worshipped? Not completely. Not yet. It's just around this bend,' Fulano said. 'Prepare yourselves. The next-to-ultimate revelation will stun your… Well, why should I tell you what to expect? See for yourselves.'

He led. They followed, and as Tess rounded the bend, she gasped, not only in awe but fear. So did Craig.

The chamber, like the previous one, was filled with paintings, images, life-like portrayals of animals. But here the animals were exclusively bulls. Everywhere. And unlike the paintings in the previous chamber, the bulls weren't outlined in charcoal or red. These were multi-colored, not merely silhouetted but completely detailed. Totally realistic. Their hoofs were black, their haunches brown, their humped backs red. Their tails curved as if in a photograph. Their slanted pointed horns, too, were black. And their eyes were so vivid that they seemed about to blink in rigid anger, furious that they'd been captured eternally on the walls and the ceiling, their legs thrusting, their muscles straining, their bodies arching, an example of – a celebration of – the strength of nature, the strikingly beautiful surge and power of the universe, which twenty thousand years later was on the verge of being destroyed.

'The colors come from powdered carbon, ochre, and iron oxide, mixed with animal fat and blood. The technique is known as polychrome,' Gerrard said, 'and there are only two other sites, Lascaux and Altamira, where it was used to such a degree. Immensely sophisticated. Superbly executed. The greatest artwork that human beings have ever created. Because the message is the greatest – the enormous vitality of nature. But as the green mold on the paintings at Lascaux makes clear, our interference with nature has caused its vitality to be weakened to the point of extinction. We have a sacred responsibility. At any cost, the sickness of the planet must be reversed.'

Tess felt increasingly overpowered by what she was seeing.

And increasingly fearful.

Bulls. Like flames and crosses, so much of this nightmare had to do with bulls, and while her gaze pivoted along a wall, across the brilliant multi- colored bulls, she suddenly froze at the sight of one bull that was larger than all the others. Instead of having been portrayed in red, black, and brown, it was monochrome, the white of chalk, like the bull in the statue, and its head was raised in agony, a spearlike barbed line projecting through its neck.

Tess followed the direction of the white bull's anguished expression and whimpered when she saw another locked iron door.

What had Gerrard just said? We have a sacred responsibility. At any cost, the sickness of the planet must be reversed. And earlier, Fulano had said that this chamber was the next-to-ultimate revelation. What was behind the door?

'This is the only example of a violent image in the cave.' Fulano interrupted her urgent, panicked thoughts. 'But my ancestor wasn't puzzled. He understood the necessity for the violence in the painting, and he also understood that the color of the bull, its whiteness, was a sign. He knew precisely what he had to do.'

Tess gripped Craig's hand, watching Fulano unlock the door, then shove it open, the shriek of its hinges making her spine quiver.

'Somehow I don't think we're going to see more paintings,' Craig said.

'You assume correctly,' Fulano said. 'What you're going to see is the truth.'

Tess gripped Craig's hand much harder. In dismay, she hesitated. But Hugh Kelly and the guards urged her onward. With dread, her stomach cramping, she had to step through the door.

TWELVE

The cavern was dim, illuminated sparsely not by lightbulbs but by torches. The cavern became darker when Fulano shut and locked the door, blocking the light from the bulbs in the chamber of the bulls.

'The floor is damp but level. You shouldn't have trouble maintaining your balance,' Gerrard said, reassuringly. Their footsteps echoed. As Tess approached the first of the torches, she saw that it was made of stone and anchored into the cavern's floor. At the top, a basin was filled with flaming oil. The tongues of fire wavered as if her approach had caused a subtle breeze.

She stepped toward a second torch, and beyond in the darkness, she heard Gerrard and Fulano walking. Something scraped. A match flickered. She saw Gerrard lower it toward another torch, from which flames soon rose. Fulano did the same, lighting a farther torch. The two men moved around the chamber, continuing to light more torches until the darkness was almost completely dispelled. Even so, when they passed the torches, their shadows wavered eerily.

Fulano had described the cave paintings as the Sistine Chapel of paleolithic art. But now, in shock, Tess found herself staring at a true chapel. She tried to retain her presence of mind, to analyze what she was seeing. The chapel's design, its columns and vaulted ceiling, looked Roman, but given what Fulano had said about the cave having been discovered in the eighteen hundreds, Tess suspected that no matter the chapel's design, it wasn't ancient but instead had been built within the past hundred years.