She shook her head. Sometimes he and Jason were frighteningly similar. "If everyone is ready," she said, "let's proceed. I want to be into the new territory by the time we set up camp tonight."

Ashley hesitated.

"Just a little farther," Ben called to her from below.

Sucking at her lower lip, she stared down the steep slope before her. It looked more like a mile. Greased with mud, the cliff was slick as ice. Her eyes snaked upward, following her rope. Michaelson was snugged into a crevice several yards above and secured in place with a safety rope. Above him, at the lip of the cliff, hung Villanueva, clinging to a spur of rock and secured with a safety line. It was these two men's jobs to ensure a safe descent for the other teammates.

Ashley took a deep breath and pushed away from the wall as she had been instructed, allowing the rope to brake in the carabiner bars to stop her descent. She scrabbled downward, the toe of her left boot balancing on a protruding stone. Just a little farther.

The stone that had been supporting her suddenly slipped loose and tumbled downward. She plummeted after it, the rope racing between her gloved hands. Ben had schooled them to yell, "Falling!" when this sort of thing happened, but with her breath caught in a fear-constricted grip, all she could do was let out a high-pitched whine.

After a heartbeat, the whistling rope snagged in her carabiner and her descent jerked to a halt. A grunt of protest echoed from above as Michaelson caught her weight.

"Hey, careful up there," Ben yelled. "You damn near gave me a rock facial."

"Sorry," she said to the muddy wall swinging inches from her nose, both hands clamped on the rope.

"C'mon, relax, kid," Ben said. "Just get those feet back on the wall and finish the descent. You're almost on solid ground."

It was the solidness of that ground that concerned her. She had pictured her head slamming into that solid ground as she was falling, but she wasn't about to remain hanging here. There was only one way out of this predicament. Pulling into a squatting position, she got her boots up on the wall and straightened her legs out, pushing from the wall. With a jump, she rappelled down two yards and caught the wall with her boots. Not hesitating this time, she shot outward again and dropped another couple of yards. After two more hops, she felt Ben's arms around her waist.

"There you go," he said in her ear. "Piece of cake."

She settled her legs on the rocky floor, her knees wobbling a bit. "Yeah, no problem."

"This is good practice. Luckily we came across this bunny slope the first day. I'm sure there's hairier cliffs ahead of us."

She craned her head back. Villanueva was just a blur of light at the edge of the cliff above. She suppressed a groan, leaning on a stalagmite. And this was only day one.

Ashley rubbed her back, lowering herself slowly onto her air mattress. She could hear Michaelson mumbling into the radio several yards away, giving his final report of the day. The team had discovered signs of the previous party's passage-discarded items, boot tracks in silt, scruffs on rock-and were sticking close to their trail.

She let out a long sigh, stretching. A sharp jab in her lower back protested the motion. Their progress today seemed more like a battle. Slippery mud covered most of the walkways; sharp gypsum crystals clung to her entire body like sand on a beach, and grew more abrasive with each step; steep slopes and sharp inclines impeded their forward movement, slowing them to a crawl.

Worst of all, though, was the heat. An omnipresent wet blanket that grew heavier as the day's journey wore on. She took off her headband and twisted it, wringing out a stream of sweat. She now understood how risky dehydration was in caving. She unscrewed the top of her canteen, almost empty now. Tipping it back, she swallowed the last warm drops.

"You'll have to watch your water," Ben warned. "We can't count on finding a water hole every day." He nodded toward the small lake pooled in the back half of the cavern, half hidden by an outcropping of rock.

"I knew about this water hole," she said. "It's on the map."

"True, but this is the last cavern marked on the map. From here, it's to points unknown."

"I know. I'll be more conservative tomorrow. We should remind everyone in the morning. Especially Linda. She ran out of water at lunch and has been borrowing from my canteen."

"Yours too, huh?" Ben said with a smile. "She finished the last of mine an hour ago."

"Clever girl," Ashley said. "By the way, where is she?"

"Over at the pond… getting a drink of water."

She shook her head. "Tomorrow we'll need to be more strict with rationing."

"Oh, just leave her be. I was just joking. She's over there doing a water analysis. Besides, she's having a tough time of it."

"We all are."

Ben gestured toward the two SEALs, who were setting up the campstove a handful of yards away. Light pooled around them from their lanterns. "They barely broke a sweat."

She watched as Villanueva stripped off a khaki T-shirt and wiped his face and armpits before slipping into a green vest. With a small pop, Halloway lit the butane for the campstove. Both appeared as refreshed as if today's journey were nothing more than a Sunday walk through the park, while everyone else dragged as if just completing the Bataan death march, haggard, bone-tired. Her stomach rumbled audibly.

Ben raised an eyebrow. "I'm hungry too. But there's nothing except freeze-dried beans and franks."

"Right now, that would fit the bill."

Ben grinned. "Though a beer to wash it all down… now, that would be heaven." As he sat down on his own mattress, he suddenly swatted at his arm. "Hey, something just bit me!"

"What?"

He shined a light on his arm.

She leaned over and looked at the spot. "Looks like a mosquito."

"Bloody large skeeter. Just 'bout took a chunk out of my arm."

"Quit exaggerating."

He poked her with a finger. "Wait until you get speared. Don't come crying to me."

"That's odd," she said, scratching behind an ear. "What's a mosquito doing in Antarctica? Way down here?"

Ben's expression became serious. "Good question. You don't often find insects down here. Crickets, a few spiders, centipedes, that sort of thing-but I don't think I've ever seen a mosquito."

Ashley wondered at the significance of such a discovery. "Maybe we'd better ask our biologist."

"Thanks for sharing your water today, Khalid," said Linda. "I couldn't have made it without your help."

"Anytime," he said, breathing in the dank air. He sat on a rock, watching Linda scooping water into small glass vials. He appreciated the wide furrow of moisture down the middle of her back, pasting the cotton T-shirt to her body. The clasp of her bra was visible through the thin fabric. He bit his tongue to control his rising lust.

Smiling at him, Linda stood up and sat on the boulder beside him, shaking the vial in her hand. "That last ridge was brutal. I'm glad we're done for the day."

He could feel her body heat pulsing across the hand span of space between them. They sat in silence, Linda studying the crystal surface of the pond, Khalid studying her.

"My god!" she suddenly exclaimed, jumping to the edge of the black water. "Khalid, look over here." She crouched on her knees, waving him toward her.

He crossed to her, inhaling her scent, a hypnotic perfume in the moist air. "What is it?"

She lifted a curled shell, dripping and luminescent in the lamp's glow, that had been partially hidden by a rock in the shallows. Khalid cocked his head to the side. It looked similar to a snail's shell, but it was huge. Almost the size of a watermelon.