You've got the job of sealing the entrance."

Twenty minutes later, a strange contraption sat in between the two anch.o.r.ed Zodiacs: a hollow inflatable rubber tube that dived down into the water like an opentopped vertical pipe.

Astro and Pooh Bear-in full scuba gear and bearing harpoon guns for the crocs- splashed backward into the inky water, flashlights on.

Ninety feet underneath the boats, they arrived at the lake bed, at the point where it met the base of the rock pyramid.

They panned their flashlights over the surface of the island pyramid, to revealhundreds of images cut into the rocky surface. They were mainly standard Egyptian carvings: hieroglyphics and images of pharaohs shaking hands with G.o.ds.

"Jack," Astro said into his facemask mike, "we've got carvings. Lots of them."

Pooh Bear waved a portable GPR-groundpenetrating radar-device over the image riddled wall. Kind of like an Xray, it could detect hollows and voids behind the surface of the wall. "Here! Got a void behind this carving!"

Astro shone his flashlight onto the suspect section of wall, and found himself illuminating a carving he'd seen before: The symbol for the Machine. "We should've known," he said. "Found it."

ASTRO AND POOH BEAR then quickly set about affixing a peculiar tentlike device over the point where the lake floor met the wall of the pyramid island, covering the carving of the Machine.

Shaped like a cube, the tentlike device was a portable variableaperture United States Navy submarine docking door-a gift to West from the Sea Ranger.

Normally used to join submersibles to submarines, it was a rubberwalled docking unit that operated like an air lock: once you affixed it in place, sealing the edges, you filled it with air-inflating it like a balloon and expelling any water from it-thus providing a dry "docking environment" between two submerged points.

There were removable entry holes in each of the cube's six sides, and at the moment one of these-on the upper side of the docking unit-was connected to the tube that snaked back up to the Zodiacs.

Once the unit was in place, its corner points bolted to the lake floor and to the pyramid island itself, Jack started an air pump, filling the tube and the docking unit with air.

The docking door inflated quickly and suddenly the way was clear to climb down its tube-perfectly dry-and access the wall of the ancient pyramid island.

Jack climbed down the rubber tube, gripping its inbuilt ladder holds, slowly descending into Lake Na.s.ser.

He carried a fullface scuba mask but did not wear it. It was a precaution, just in case the docking door collapsed or otherwise unexpectedly filled with water. He also held the cleansed First Pillar in a chest pack. On his head he wore his trademark fireman's helmet.

He came to the bottom of the entry tube and stood-thanks to the airfilled docking unit- on the floor of Lake Na.s.ser. His boots stepped down into an inch of water, water that formed a suction layer against the bottom of the tentlike docking unit.

The exposed flank of the pyramid island stood before him, rocky and uneven and glistening wet.

Carved symbols covered it, a kaleidoscope of images in which the carving of the Machine was easily lost.

But there was no discernible door in the wall. Nothing but carving after carving after carving.

Jack gazed at the symbol for the Machine.

It was a fairly large carving, about the size of a manhole. And the six rectangles in it depicting the six Pillars seemed to be lifesized, the same size as the Pillar in Jack's chest pack.

Unlike all the others, however, the uppermost rectangle in the carving wasindented, recessed into the image.

"A keyhole," Jack said aloud.

He removed the Pillar from his chest pack, held it against the recessed rectangle.

It was an exact match for size.

"You'll never know if you don't try..."

And so he reached forward with the Pillar and pressed it into the rectangle- -and immediatelythe entire circular carving turned on its axis, rotating like a wheel, and retreated into the wall, revealing a dark round tunnel beyond it.

Jack stepped back in surprise, still gripping the Pillar.

"Jack? You OK down there?"Zoe's voice asked in his ear.

"Am I ever," he said. "Come on down. We're in."

THE TUNNEL OF SOBEK.

THE TIGHT TUNNEL beyond the round entry hole was slick with wetness. A dripping noise echoed from somewhere within it.

Gripping an amber glowstick in his teeth and guided by the light on his fireman's helmet, Jack bellycrawled for about five yards down the claustrophobic tunnel before he came to its first obstacle: a huge Nile crocodile, easily an eighteenfooter, blocking the way and grinning at him from a distance of three feet.

Jack froze.

The thing was enormous. A great fat prehistoric beast. Its fearsome teeth protruded from the edges of its snout. It snorted loudly.

Jack shone his helmet flashlight down the tunnel past the big croc, and saw others beyond it, maybe four more lined up in single file down the length of the tight little tunnel.

There must be some other entrance,Jack thought.A crevice somewhere above the waterline that the crocodiles have slithered in through.

"Hey, Jack?" Zoe said, arriving in the tunnel behind him. "What's the holdup?"

"A large animal with a whole lot of teeth."

"Oh."

Jack pursed his lips, thinking.

As he did so, Zoe came up behind him and shone her flashlight past him. "Oh, you have got to be kidding me."

Then abruptly Jack said, "It's too cold."

"What?"

"It's too early in the day for them, their blood's still too cold to be a threat."

"What are you talking about?" Zoe asked.

"Crocodiles are coldblooded. For a croc, especially a big one, to perform any kind of athletic act, it needs its blood to be warmed up, usually by the Sun. These guys are scary, sure, but it's too early in the morning for them, too cold, so they're not gonna be capable of big aggressive movements. We can crawl past them."

"Now you really are kidding."

At that moment, Pooh Bear and Wizard arrived behind them.

"What's the problem?" Pooh Bear asked.

"Them." Zoe jerked her chin at the line of large crocodiles before them. "But don't worry, Captain Courageous here thinks we can crawl by them."

Pooh Bear's face went instantly white. "Crcrawl by them...?"

Wizard gazed at the crocs, nodding. "At this time of day, their blood will still be very cold. The only thing they could really do right now is bite."

"Biting is what worries me," Zoe said.

Jack checked his watch. It was 5:47A.M.

"We've got no choice," he said. "We've got twentyfive minutes to get to the Vertex, and that means getting past these guys. I'm going in."

"Er, Huntsman," Pooh Bear said. "You know...well...you know I'd follow you anywhere. But I'm...not good with crocs at the best of times and this is-"

Jack nodded. "It's okay, Zahir. No one's completely fearless, not even you. You sit this one out. I won't tell anyone."

"Thank you, Huntsman."

"Zoe? Wizard?"

He could see that they were thinking similar thoughts.

Zoe eyed the tunnel determinedly. "You can't do this alone. I'll be right behind you."

And Wizard said, "I've worked my whole life to see what lies beyond those crocs. I'll be d.a.m.ned if they'll stop me."

"Then let's do it," Jack said.

Crawling through the darkness, he came to the first croc.

The great reptile made him look tiny, puny.

As Jack's face came level with it, the croc opened its ma.s.sive jaws, revealing every single one of its teeth, and emitted a harsh belching grunt in warning.

Jack paused, drew in a deep breath, and took the plunge, crawling past the thing's jaws and shimmying around the side of the animal, sliding up against the curved wall of the tunnel.

His eyes came level with the croc's-and Jack saw that those eyes, cold and hard, were watching him every inch of the way.

But the creature did not attack. It did nothing but shuffle on its claws.

Jack wriggled past it, his cargo pants brushing up against the bulging belly of the beast, and he could feel the flabby give of its abdomen, and then suddenly he was alongside its spiky tail, past it.

Jack let out the breath he'd been holding.

"I'm past the first one," he said into his headset mike. "Zoe, Wizard. Come on through."

THE STAIRS OF ATUM.

IN THIS MANNER, Jack, Zoe, and Wizard slithered down the long tight tunnel, squeezing on their bellies past the five gigantic Nile crocodiles.

At the end of the tunnel, they emerged at the top of a square stone well equipped with a staircase that delved down into darkness.

The stairs bent back and forth as they dived down the well shaft. On the walls of each landing were thousands of hieroglyphs, including more large carvings of the Machine's wheellike symbol.

Jack descended the first flight of steps and came to the first landing......where the Machine symbol in the wall retreated inward by some unseen mechanism and revealed a wide gaping hole behind it, a hole that could contain any kind of deadly liquid...

...but then the Pillar in Jack's hands glowed slightly and the hole instantly resealed itself.

Jack exchanged a look with Wizard.

"Doesn't look like you get past these traps without the Pillar in your possession."

"Not without great difficulty," Wizard agreed.

Down the stairs they climbed, winding back and forth.

At every landing, the wheellike symbol for the Machine opened but then closed again when it sensed the Pillar in West's hand.

Down and down.

Wizard counted the stairs as they went, until at last they came to the bottom, where the stairs stopped at a great stone archway-tall and imposing, twenty feet high. It opened onto dense blackness.

Wizard finished his count-"267."

Jack stepped into the archway, staring out into the blackness beyond it. A light breeze struck his face, cool and crisp.

He sensed a large s.p.a.ce before him, so he pulled out his flare gun and fired it into the black.

Fifteen flares later, he just stood there in the archway, his mouth open in wonderment.

"Now that's a sight you'll remember for a long time," he breathed.

THE HALL OF THE MACHINE.

The twenty foot high archway in which Jack stood looked microscopic compared to the s.p.a.ce that opened up below it.

The archway stood at the summit of an immense mountain of stone steps-five hundred of them, maybe more-steps that descended to a flatfloored hall that was easily four hundred feet tall and five hundred wide. The colossal collection of stairs stretched for the entire width of the hall, from wall to wall, an enormous mountainside of perfectly square cut steps.

The ceiling of this mighty subterranean hall was upheld by a forest of glorious columns, all of which were carved in the colorful Egyptian fashion, with brilliant redblueand green lotus leaves at their tops. There must have been forty such pillars, all in regular rows.

"Just like the temple of Rameses II at Karnak..." Wizard breathed.

"Maybe the temple of Rameses was a replica built in honor of this," Zoe said.

Standing at the top of the great flight of stairs, Jack felt like he was standing in the topmost row of a modern football stadium, gazing down upon the field far below.

And there was one other thing.