Dr. Andrew Dart was thirty feet up the side of the limestone wall when a jagged rock glanced off the face of the bluff just above his head. Dart flinched, then looked up. He saw and heard nothing.

Dart drew a shuddering breath. Chunks of limestone, loosened by wind and rain, sometimes broke away on their own. A few inches to the right and it could have killed him.

He rested on a shallow ledge and wiped his brow. From his perch he could see over the trees to where Bloodwater River flowed into the Mississippi. Not many wild places like this left.

All this land had once been populated by Native Americans. The rivers had been their freeways. They had built great villages looking out over the Mississippi River-maybe even right here, at the top of this rocky precipice.

The bluff he was climbing, and the woodland below, were owned by Bloodwater College, where Dart was a Professor of Archeology. But in a few days the land would be sold to a developer. Dart had taken it upon himself to do a final survey of the area before the bulldozers arrived. If he could find just one good piece of archaeological evidence-the ruins of a Native American village, or a burial mound-the college might be persuaded to stop the sale. Even a single unusual artifact might be enough.

Dart resumed his climb. Moments later, he had reached the odd cleft in the rock he had seen from below. There was a concealed opening, a crack in the bluff just wide enough for a man to squeeze through. He sniffed. Bat guano.

He stood in the entrance and tried to get a grip on himself. He hadn't planned on exploring a cave. All he had was the small flashlight attached to his keychain. And he did not like dark places. But this was important.

He forced himself to take a few steps into the cave, then stopped and let his eyes adjust to the dark. The passageway was narrow and low. He ducked his head and followed the weak beam of his flashlight. He felt panic rise in his chest as the passage narrowed. The rock walls seemed to be closing in on him, but forced himself to move farther into the cavern.

The passageway soon widened into a large chamber. He could hear the chittering of bats from above. Staying close to the wall, he came upon another narrow passageway leading off to the right. He saw footprints in the dust-he was not the first person to visit this cave. As he examined a footprint, he heard a shuffling noise. He froze, listening carefully, but didn't hear it again. Probably an echo.

Moving deeper into the chamber, he gasped at what he saw next. A collection of dry yellow bones lay piled against the cavern wall.

A skeleton! Was it human? Yes! He could see the skull!

He shined his flashlight into the empty eye sockets. This is just what I need! he thought.

Dart heard the shuffling sound again. He turned to look just as something smashed into the back of his head. He pitched forward, and the last thing he heard was the snapping of ancient, brittle bones.