“Teresa… please.”

There was another pause. “All right. Teresa. Um, got yours adjusted yet?”

“Just a sec.” She pulled the strap and toggled the switch by one lens. Suddenly it was as if someone had turned the lights on.

Unlike mere passive infrared goggles, which would have detected very little down here, these monitored whichever way her eyes turned and sent a tiny illuminating beam in just that direction, for just as long as she was looking that way. The only exception was where they detected another set of goggles. To prevent blinding another user, the optics were programmed never to shine directly at each other, so when Teresa looked around for the first time, she made out limestone walls, the inky waterline, the boat — but Alex Lustig’s face remained hidden inside an oval of darkness.

“Couldn’t have used them before because Spivey had spy sensors—”

Teresa waved aside his explanation. It made sense. “Now where?” she asked.

He pointed downward, and she understood why even the peeper colonel’s little robot watchers wouldn’t be able to follow them. “Okay,” she said. And together they sorted equipment from the nylon bag.

Claustrophobia was the least of her worries as they kicked along a deep, twisting tube, carried by the current of an underground stream. Nor did the bitter cold bother her much — though Teresa kept an eye on the tiny clock readout, calculating the time before hypothermia would become a problem.

Alex’s flippers churned the water in front of her, creating sparkling flecks in her goggles’ beam. Spectrum conversion always made things look eerie, but here the effect was otherworldly, other-dimensional. The taper of his legs seemed to stretch endless meters, kilometers ahead of her, like this surging hypogean torrent.

The river held their lives now and they were helpless to turn back if George Hutton’s map proved wrong or if they took some fatal wrong turn. She imagined they might, as in some old movie, be swept downward ever deeper into the Earth’s twisting bowels, to some Land That Time Forgot. In fact, though, washing ashore on a misty underground dinosaur refuge was less unsettling to contemplate than some likelier possibilities… like meeting their end pinned to a porous wall, the freshet plunging past them through crevices too small for human flesh to pass.

Was Alex planning to lead her all the way to the river’s outlet, somewhere on the Tasman Sea? If so, the timing would be tight. Their air capsules weren’t rated for more than a couple of hours.

Perhaps it was the coolness, but Teresa’s thoughts soon calmed. She found herself wondering at the sculpted shapes of the sweeping, curving tube… at the way different hardnesses of stone overlapped in smooth relief and how patient eddies had carved cavities into the ancient mountain, laying bare fine patterns, delicate to the eye.

Those eddies were dangerous. Even with gloves and knee pads it was hard to ward off every sudden invisible surge, every buffet and blow. Teresa felt certain there were daredevils among the world’s bored, well-fed majority who would pay George Hutton handsomely for this experience, without ever understanding where they were or what they were seeing.

At one point the river opened into a large chamber with an air pocket. They met at the surface, spitting out their mouthpieces as they treaded water.

“Amazing!” she gasped. And the black oval covering his face seemed to nod in agreement. “Yes, it’s unbelievable.”

“Where to from here?”

“I… think we take the way to the left,” he answered after a pause.

Teresa churned her legs, rotating. Yes, the river split here, dividing into two unequal paths. Alex was referring to the narrower, swifter-running branch. “You’re sure?”

In answer, he held out the miniplaque that hung from a cord around his neck. “Did you see any other large chambers on the way here? Did I miss one?” She peered at the sketch. A computer graphics device could reproduce only what it was given, and George Hutton’s drawing had apparently been scrawled in a hurry. “I… I’d have to say you’re right. Left it is.”

They reset their goggles and mouthpieces and kicked off toward the left-hand opening, and an ominous roaring. Teresa was intensely aware of the annotation Hutton had inscribed at this point on the map, in red letters.

Be careful here! the inscription had said.

Only a few meters into the new stretch, Teresa realized just how friendly the last one had been. No time or energy could be spared for sightseeing or philosophizing now. Curves loomed suddenly out of the froth ahead, confusing her smart goggles. Confusing her. Even with the help of slip-streaming — the natural tendency to ride the current’s center — it took every ounce of effort just to keep the writhing stone intestine from crushing her!

It can’t be much farther, she figured, remembering her brief glimpse at the sketch, unsure whether she was calculating or simply praying. The last pool has to be just ahead.

No sooner did she think that though, than suddenly she was caught in a tangle with Alex Lustig’s legs. With the river plowing into them from behind, the collision was a series of buffets that made her head ring, knocking dazzling spots before her eyes. The goggles only made things worse by dimming suddenly in response to her pupils’ shocked dilation.

A sharp scrape on one leg made Teresa aware of jagged stones, too fresh and rugged to have lain in the smoothing flow for long. A rockfall must have partly blocked the stretch of river. She writhed to one side barely in time to avoid being impaled on one jutting monolith, then had to grab Alex’s leg as the current swept her toward another jagged jumble just ahead!

Clutching his ankle, Teresa hadn’t time to wonder how he had stopped so suddenly. She held on tightly with both arms. Her flippered feet bumped the barricade and instinctively she kicked at it.

Miraculously, it gave way! Glancing quickly downstream, Teresa saw the current sweep away what remained of the precarious barrier. All it had taken was one extra nudge and the impediment was gone. What luck!

She almost let go to continue the journey. But then she paused. How is he holding on? a voice insisted. And why doesn’t he let go now that the way is clear?

Something else had to be wrong. Involuntary shivers were coursing down the man’s legs. He’s in trouble, she realized.

Fighting the current, worming her arms forward one at a time, Teresa climbed up his legs inch by awful inch, seizing at last a solid grip on his belt. She lifted her head to see what Alex was doing.

My God! Bubbles escaped Teresa’s mouth as she tried not to cry out. The goggles prevented her from looking within the circle of darkness framing the man’s face. But she didn’t need any look in his eye to know panic and despair. With growing feebleness, Alex clawed at a thong that gouged deeply into his neck, releasing thin trails of blood every time the current let up a bit. That same current almost dragged Teresa’s goggles off as she shifted to try to see around the black circle, to whatever had him trapped.

It was the map plaque. Somehow it had jammed into a crevice left by the cave slide! It was what had stopped them both from crashing among the razor-sharp rocks just seconds ago. Now wedged in place by Alex’s struggles, it also anchored the noose that was strangling the life out of him.

There was no time for thought. Teresa’s knife was at her ankle, while Lustig’s was convenient at his thigh. It would have to be his then. But to take it meant she’d have to let go with one arm! And Teresa knew she couldn’t hold on… unless.

She took three deep breaths, spat out her mouthpiece and bit down hard on his belt, fastening her teeth as hard as she could. Gripping tight with her left arm, she released the right and fought to bring it to the knife. The river buffeted them like flags. But in spite of the pain, her jaw and shoulder remained in their sockets as her right hand fumbled with the sheath snap and at last brought out the gleaming blade.