Chapter One STOP. We have a fatality. BILL STONE, HALF A MILE DEEP and three miles from the entrance in a Mexican supercave called Cheve, did stop. Red-and-white plastic survey tape hung across the narrow passage he had been ascending. The message, scrawled on notebook paper, was affixed to the tape at chest level, where it could not be missed. Afloat in the cave''s absolute darkness, the white paper burned so brightly in the beam of Stone''s headlamp that it almost hurt his eyes. The time was shortly before midnight on Friday, March 1, 1991, though that made no particular difference--it was always midnight in a cave. Stone, a hard-driving man with a doctorate in structural engineering, stood six feet, four inches tall and weighed two hundred hard-muscled pounds.

He was one of the leaders (two veteran cavers, Matt Oliphant and Don Coons, were the others) of an expedition trying to make the last great terrestrial discovery by proving that Cheve (pronounced CHAY-vay) was the deepest cave on earth. He had brown hair, a long hatchet face, a strong neck, intense blue eyes, and a prow of a nose angling out between them. Stone was not classically handsome, but it was a striking, unsubtle face men and women alike looked at twice. Not just now, though. Having been underground for almost a week nonstop, he was gaunt, haggard, and hollow-eyed, his cheeks rough with scraggly beard, and he resembled somewhat the Jesus of popular imagination. A week underground was long, but not extremely so by supercaving standards, where stays of three weeks or more in the vast underground labyrinths were not unusual. With three companions, he was halfway through the grueling, two-day climb back to the surface from the cave''s deepest known point, something like 4,000 vertical feet and 7 miles from the entrance. The note and tape had been strung just before the expedition''s Camp 2, where four others were staying.

They explained to Stone what had happened. At about 1:30 p.m. that day, a caver from Indiana named Chris Yeager, twenty-five years old, had entered the cave with an older, more experienced man from New York, Peter Haberland. Yeager had been caving for just two years, and going into Cheve was, for him, like a climber who had been on only small Vermont mountains suddenly tackling Everest. This is not a specious comparison. Experts affirm that exploring a supercave such as Cheve is like climbing Mount Everest--in reverse. Not long after he arrived in camp, more experienced cavers nicknamed Yeager "the Kid.

" Seriously concerned about the younger man''s safety, a veteran, elite cave explorer named Jim Smith sat Yeager down for what should have been a sobering, thirty-minute lecture: don''t go into the cave without a guide, carry only a light daypack at first, learn the route in segments, get "acclimatized" to the underground world before going in for a long stay. The warnings fell on deaf ears. Yeager started his first trip with a fifty-five-pound pack, planning on a seven-day stay. Yeager''s problems began soon. Just three hours into the cave, he did not properly secure his rappel rack (a specialized metal device resembling a big paper clip with transverse bars, built for sliding down long, wet ropes with heavy loads in caves) to his climbing harness. As a result, he dropped it. The rappel rack is a critical piece of equipment for extreme cave exploration, probably second in importance only to lights. Without his, Yeager could not continue.

Yeager used his partner''s rack to descend to the area where his had landed. Given that a rappel rack is about 18 inches long and Cheve Cave is almost unimaginably vast and complex, this was rather like looking for a needle in a thousand haystacks. Yeager was lucky indeed to find his rack, which allowed him to continue down with Haberland. They did not keep descending for long, however, because they quickly got lost and could not relocate the main route for forty-five minutes. After seven hours, they arrived at the top of a cliff that had been named the 23-Meter Drop because it was exactly that, a 75-foot free drop from lip to pit that had to be rappelled. By supercaving standards, where free vertical drops hundreds of feet long are common, this was little more than a hop down. Haberland went first, completing an easy rappel without incident. At the bottom he detached his rack from the rope, then moved away to avoid any rocks Yeager might dislodge.

Above, Yeager was wearing standard descent equipment, which included a seat harness similar to those used by rock climbers but beefed up for the heavier demands of caving. A locking carabiner (an aluminum loop, about the size of a pack of cigarettes, with a hinged "gate" on one side) connected the harness to his rappel rack, and the rappel rack connected him to the rope. The rope wove through the rack''s bars, like a snake sliding over and under the rungs of a ladder, providing enough resistance for a heavily laden caver like Yeager to control the speed of his descent. Before going farther, Yeager had to transfer his rack from the rope he had been descending to a new one that would take him to the bottom of the 23-Meter Drop. He made the change successfully, leaned back to begin his rappel, and realized instantly that something was wrong. The rope did not stop his backward-tilting motion. Instead, he kept going, as if tipping over backward in a chair. Somehow his harness had become separated from the rappel rack, which was still attached to the rope.

Instinctively, he lunged to grab the rope and the dangling rappel rack. Had he been carrying no pack, or even a light daypack, it''s possible that he might have saved himself by holding on to the rope, or to the anchor bolted to the wall, or perhaps even setting up something called a body rappel. But that would have required almost superhuman strength and would have been extremely difficult even without any load. His fifty-five-pound pack made any such self-arrest impossible, and in another instant he was dropping through space. He fell so quickly that he did not even have time to scream. Falling rocks can shatter and ricochet like shrapnel; Peter Haberland had moved off and sheltered behind a boulder, so he did not see Yeager land. He realized something was wrong only when he heard a rush of air and the crunching impact of a long fall ending on solid rock. Praying that Yeager had dropped his pack, Haberland called out, but he got no answer.

Within seconds, Haberland found Yeager, lying beside the bottom of the rope. He was in a pool of water three inches deep, on his right side, his face partly in the water, his arms stretching forward, as if reaching for something. Yeager''s right leg was broken, the foot rotated grotesquely 90 degrees so that while the body was on its side, the foot pointed up. He had no pulse or respiration, but Haberland turned his face slightly anyway, to keep his mouth and nose clear of the water. Haberland rushed down to the Cheve expedition''s Camp 2, a twenty- minute descent, where he found two other cavers, Peter Bosted and Jim Brown. They left a note hanging from red-and-white survey tape and rushed back up to Yeager''s position with a sleeping bag and first aid supplies. When they arrived, they found that some blood had run from his nose, but there were no other changes. All three attempted CPR without success.

Chris Yeager was dead. Understanding precisely why the accident happened requires a detailed knowledge of caving equipment. But the root cause was not equipment failure; it was "pilot error." Yeager entered the cave with too much weight, became fatigued, misused his equipment, and, last and worst, failed to properly secure the locking carabiner that connected his harness to the rappel rack. He apparently made this mistake not just once but twice, the first instance having caused the rack''s earlier loss. LEARNING OF THE ACCIDENT, Bill Stone could only shake his head in dismay. He had been uneasy about Yeager''s presence in camp in the first place. Yeager; his girlfriend, Tina Shirk; and another man traveling with them had not been part of the original expedition.

After climbing some volcanoes, the three had traveled to the Cheve base camp. Shirk was a competent caver who had been in Cheve the previous year but, with a broken collarbone, was not caving just then. The other man had told Shirk and Yeager that, earlier, he had secured permission for Chris to go into the cave. There is some disagreement about that, but Stone, for one, knew nothing about it. As far as he was concerned, the trio had "crashed" the expedition. Yeager''s death affected everyone. Peter Haberland later wrote in a caving magazine article that he was "shattered at that moment." Tina Shirk was devastated.

Other reactions ranged from anger at an overzealous rookie to grief over a young man''s death to horror at the reality of a body decomposing down in the cave. For his part, Bill Stone was saddened by the needless loss of a young man''s life. He was angered because Yeager''s death left the leaders and the team with a thorny problem that could be solved only by endangering others. And he was afraid, not so much of recovering Yeager''s body, but that his death might abort the expedition. They could have been on the verge of finding the way into Cheve''s deepest recesses and, it was not ridiculous to assume, possibly into history as well. But now it seemed likely that this expedition''s time had run out all too soon. Stone was completely committed to the expedition''s mission, financially, emotionally, and physically. The intensity of his work, and his no-nonsense style, left no doubt about that in anyone''s.