SILENCE NOW. TEN LONG HEARTBEATS HAD PASSED SINCE the scream had blasted from the tunnel. The dark entrance was beginning to clear of smoke from Villanueva's assault. Was it killed? Swallowing hard, Ashley stared down the length of her pistol's barrel. From the corner of her eye, she could see Halloway's head; it still lay a yard from her toe, staring at her as if asking why she let this happen.

She risked a quick glance toward Ben on her right. He caught her look and shrugged. Maybe whatever killed the SEAL was dead. Maybe they had lucked-

With a bellow, it burst from the tunnel.

A flash of teeth, needle-sharp and serrated.

"Christ!" Ashley yelled. In shock, she stumbled backward, losing her shot.

Ben knocked her to the side, out of the way of the lunging jaws, then hauled her behind a jumble of boulders.

Somewhere far off she heard Linda screaming.

"What the hell-" Ashley began, but Ben silenced her with a hand over her mouth.

A foul carrion scent flooded their hiding place as a massive snouted head, reptilian, like a crocodile, swung over the lip of a boulder, weaving on a scaled neck; its nostrils, open wide, snorted the air, searching. Oily black skin stretched over skull and jaw. Then its snout swept toward them, rolling a lidless black eye, like a chunk of polished obsidian, in her direction.

Beside her, Ben struggled to free his rifle, to swing it around, but the narrow space behind the boulder was too small.

Ashley went to raise her pistol, but her hand was empty, the gun lost in the fall. Shit!

Villanueva stood his ground, silent, fearing movement would distract the beast and ruin his shot. He studied his target, searching for a weakness.

What the hell was it?

Villanueva squinted through his rifle sight. It stood ten feet tall, pitch-black, towering on two heavily muscled hind limbs, balanced with a thick tail. Its arms, spindly when compared to the muscled hind limbs, ended in articulated claws like some feral cat. He could see the claws, razor-edged, extending and retracting as it scrabbled at the boulder's surface.

Villanueva continued to watch as it stalked back and forth, its head out of sight behind the boulder. The hooked scimitars of its hind limbs gouged the cavern floor.

How to kill it? The creature was thick across the chest, layered in mud and scales that looked iron-hard. Could a rifle blast to the chest penetrate to the heart? Maybe. But it was risky. He would get only one shot. He swung his rifle sight forward. It would have to be the head.

The creature still probed behind the pile of boulders where Ben and Ashley had fled, keeping Villanueva's target out of sight. Suddenly its body tensed; its tail stopped twitching. It had discovered something behind that boulder… and he could guess what that was-either Ben or Ashley.

A loud hiss arose from it. Like a rabid dog raising a hackle, a ridge of spiked bristles sprouted in a crest along the back of its snaking neck, tracing down the length of its body.

Show me your head, you fuckin' monster, Villanueva thought. Gimme one clean shot.

He ground his molars. A nonfatal shot would just enrage the beast, making a second shot impossible. He tried to will it to move. Helpless, he watched the beast's muscles bunch up as it prepared to spring on its quarry.

He had to distract it!

Villanueva's knuckles whitened as he gripped his rifle.

Retreat, thought Michaelson. Linda and Khalid were his responsibility.

He huddled behind the sheltering boulder. He hated to abandon the others, but he was in no real position to offer any help. He glanced over at Linda, who still shook in Khalid's arms. They needed to retreat to a more defensible position.

He pushed off the boulder and scrambled next to them. "Grab your packs. We're heading out."

Linda raised a white face from Khalid's shoulder. "But the others?"

"Now!" he said hoarsely, shoving her pack toward her.

Khalid tossed his pack over a shoulder and helped Linda pull hers on. "He's right. We can't help them."

Michaelson, with his rifle in hand, herded his two wards forward. As they passed around the first boulder, a panoramic view of the bowl-shaped cavern opened up before them. Here at the lip, Michaelson had a view of the sloping valley they had crossed just an hour ago.

"Shit!" he said, stopping.

Khalid stood at his elbow. "What is it?"

"Over there. Just past the next ridge of rock."

Khalid looked where he pointed, then said something foul in his native tongue. Linda crushed her face into his shoulder.

Michaelson studied the view. Four reptilian heads swayed above the boulder-strewn floor, long necks stretched upward, looking in their direction. Like malignant prairie dogs. As he watched, one of the heads lowered out of sight.

There was no telling how many of them were out there, but one thing was sure: An attempt to cross would be suicide. Their retreat was cut off. Jaw tight, he wound his hand tighter into the rifle's strap.

A sudden motion caught the corner of his eye.

He swung his light to the left. Ten yards away stood a stocky stalagmite, like thousands they had passed to get here. Nothing moved there now. He clenched his jaws, tightening his grip on his rifle. Was there something behind it? Suddenly the stalagmite sprouted a snaking tail and a snouted head, perfectly camouflaged against the oily rock. Even lit up, it was hard to say where the rock began and beast ended.

The black eyes swung in his direction. Its mouth opened, revealing row after row of teeth.

Ashley cringed as the snout turned in her direction. It hissed, its breath reeking of carnage. Reaching blindly for any weapon, her hand fell upon the flashlight attached to her belt. Maybe she could club it away. Grabbing the thick handle, she swung the flashlight forward.

Ben stopped his struggle to dislodge his rifle. "Turn it on!" he yelled. "High beam!"

Reacting spontaneously to his command, she clicked the lever all the way up. A spear of light lanced out of their hiding place, stabbing the beast squarely in the eye.

Roaring, the creature snapped its head away.

As it retreated beyond the ridge of the boulder, an explosion of rifle fire erupted. Villanueva, she thought. He's still out there. She pushed onto her knees. A second round of rifle fire, this time from behind them. Ashley turned a questioning eye on Ben.

"Go!" he yelled.

She sprang to her feet, jumping a few steps away, clearing room for Ben, just as another blast of rifle fire exploded from ahead.

A scream of hissing rage echoed through the cavern, followed by a loud crash into the boulders.

"Watch out!" Ben shoved her from behind.

Falling forward, she rolled onto her side and saw the cascade of boulders tumble between her and Ben, filling the space where she just stood. "Ben!"

From behind the wall of rock: "I'm okay!… But I don't see a way to get to you!"

"Then try for Michaelson!"

"Bloody hell, I'm not leaving you!"

"Go!"

Not waiting any longer, fearing for Villanueva, she cautiously crept to the front of the boulders and peeked beyond its edge.

Her eyes widened in terror.

Villanueva's shot went sour, missing the head and glancing harmlessly off the beast's neck, but it was enough to draw its attention.

It struck at him, like a riled snake.

The mouth snapped at where the SEAL had been standing, but he had already hopped several yards back. It opened its mouth and bellowed, its eyes reflected red. He backed up another faltering step. The beast's head lowered closer to the ground, its body bunched close behind, taut with quivering muscles.

It was going to lunge.

Aiming from the waist, Villanueva pulled the rifle's trigger as the beast burst toward him. The shot hit home, striking the beast in the shoulder, a spout of blood flying.