THE RUSH OF NEWS STORIES from the slopes of Everest this spring reduced the mountain to a kind of Himalaya Horribilis, where human ethics crumble under the mountain's terrible grind. What most of these stories did not mention was that far off-stage, in a very different scrum zone—the decidedly thick air of a London courtroom—the very business of guiding was being tested. There, in Southwark Crown Court, an unprecedented criminal lawsuit threatened to put the entire expedition industry under scrutiny.

The case, unfolding at press time, concerns 22-year-old Michael Matthews, who on May 13, 1999, became the youngest Briton to scale Everest, then vanished on his descent. Matthews hadn't scrimped on expense, paying $40,000 to the Sheffield, England–based Out There Trekking, an outfitter with an impressive safety record. But he'd struggled with exhaustion during the climb up, and OTT's lead Sherpa, Lakpa Gelu, had advised him to turn back. Despite the warning, he went on to reach the top, accompanied by OTT guide Michael Smith. As the men climbed down, a blizzard swept in. Smith went ahead to clear the fixed ropes of accumulating snow. He never saw Matthews again.

Smith told London's Mail on Sunday that he'd tried to make it up the slope to find Matthews, but the storm beat him back. After waiting an hour, feeling his feet

"Our boy died, and we've looked into the reasons why," said David Matthews. "What we've found is a shocking tale of deceit and desertion."

go numb with frostbite—he would ultimately have a toe amputated—Smith said he was faced with a stark choice: "Do I stay there and wait ad infinitum and fall asleep and never wake up, or go down?" Smith said he consulted with Nick Kekus, the team leader, who was stationed at the South Col. Kekus told him the choice was his; Smith decided he had to descend.

I first wrote about the Matthews incident for the London Observer, in 2001, when Michael's father, self-made millionaire David Matthews, was preparing to file a civil lawsuit against OTT. Insurers for OTT would eventually pay an undisclosed amount in an out-of-court settlement, admitting no liability. Matthews, meanwhile, continued to investigate his son's death, which he increasingly believed was caused by negligence—something that, as he saw it, plagued commercial expeditions.

One of the team's oxygen suppliers, Matthews discovered, was Henry Todd, a longtime Everest outfitter who also refills used oxygen canisters and sells them to scores of climbers each year, saving them the exorbitant cost of buying new top-of-the-line Russian-made Poisk bottles. No oxygen system is failure-proof, so it's crucial to bring backups, climbers say. Once you do that, "it makes sense to recycle—it's silly not to," as New Zealander Guy Cotter, owner of Adventure Consultants, told Wellington's Dominion Post this year. The veteran guide said he brings new bottles for summit climbs, along with refills from Todd, adding that his company has not had problems with them. But in 1999, Todd was offering Poisk regulators wedded with British bottles; the hybrids sometimes required modification on the mountain before they worked properly, but by summit day they operated satisfactorily, OTT said.

Matthews was unconvinced, and in December 2005 he took the extraordinary step of filing a private criminal prosecution, in which a citizen pursues legal action in place of the state. Believing that negligent guiding and defective oxygen equipment left his son debilitated and at risk, Matthews alleged that Smith, former OTT co-director Jon Tinker, OTT itself, and Todd were guilty of manslaughter.

At first, as Matthews explained it to me, he'd believed what he'd been told by OTT—that his son's death was an accident and that the outfitter was in no way to blame. Two months later, however, he received a phone call from John Crellin, one of Michael's fellow OTT climbers. Crellin said some of the team's oxygen equipment had failed or was substandard, an allegation that Matthews would later hear from two additional OTT clients.

Because of a gag order, all parties in the suit are barred from discussing it with reporters, but Todd, Smith, and Tinker have strenuously denied any wrongdoing. Tinker became ill during the expedition and had already left the mountain by the time Michael Matthews died; OTT has since folded. For his part, Todd says his oxygen supplies are safe and always have been.

"I have a legitimate business which is tested and proven," he told me in 2001. "People who use my service take huge risks. I can't afford to let them down."

At press time, the judge in the case was preparing to decide whether to dismiss the suit for lack of evidence or let the matter proceed to a trial this fall. If convicted, the defendants could face lengthy jail terms.

"Some will suggest that we're wealthy people who want to make people suffer for the death of our son," Matthews told me in 2001. "But our boy died, we've looked into the reasons why, as most loving families would do, and what we've found out is a shocking tale of deceit and desertion."

Whatever the outcome of the case, guides fear it will usher in a new age on Everest—the liability era. Even if this suit is dismissed, it may be only a matter of time before similar disputes end up in court, they say. Nothing can truly protect them from grieving family members or wrathful clients.

Consider the recent example of Dan Mazur, the SummitClimb expedition leader who helped rescue Lincoln Hall. Mazur says that, this spring, his company also rescued an Argentinian client, Juan Pablo Milana, from the Second Step.

"Dude, he was facedown in the snow mumbling Ave Marias," Mazur says. "Literally."

How does Milana remember it? He says the rescue never happened and faults SummitClimb for failing to give him medical help when he suffered altitude sickness, leaving him to climb down by himself. "I am considering suing them for irresponsible behavior that put my life in danger," he said. "I lost the summit because of them."