Water dripping from the ceiling laid a slippery layer over gold-colored stone that poured over the lip into the void. Two stalagmites, just more than knee high, protruded like eyeteeth on either side of the trail. A climbing rope was anchored to one of them, its hefty weave of nylon looking as insubstantial as a spider's web in the formidable throat of limestone.

"Boulder Falls," Iverson told Anna. "More a pit than anything, but 'Boulder Pit' lacked poetry. The descent is one hundred eighty-five feet. Half of it free fall. Me first-"

"Me last," Holden finished.

Iverson hooked up his descent gear and, bracing a foot to either side of the line, walked backward, his weight on the rope, his body angled out over the shaft.

The descent didn't frighten Anna. She trusted her gear and her ability. It was the thought of going yet deeper into the ground, farther from the light of day, that made her queasy. She turned her back on the falls and looked at the already familiar face of Holden Tillman. He reached up and switched off his headlamp. "You might want to do the same," he said. "Save batteries every chance you get."

Anna clicked her light off and was instantly lost in a universe of such utter blackness that she had a sense of vertigo. Afraid to move so much as a centimeter in any direction, she sat down cross-legged where she was. An unwelcome wetness seeped through the seat of her trousers. Should anyone notice, she hoped they wouldn't think the moisture had originated from within. Given the shock of total light deprivation, it was not impossible.

As she sat in the seep puddle, the darkness began to harden around her. It was not a mere absence of light, it was a substance, an element, a suffocating miasma that filled her ears, clogged her nostrils, bore down on her shoulders and chest. When the pressure on her eyelids became such that she could feel the black leaking like raw concrete into her brain, she reached up and switched on her lamp.