Pitt retrieved a bottle of Pacifico beer from the refrigerator and joined Marquez in the garage. Marquez was hunched over a fifty-gallon drum that he had converted into a smoker. "Smells good," said Pitt. "You're not using a charcoal grill?"

"You get far better flavor from meat, chicken, or fish from a smoker," said Luis. "I shot the elk last season. Had it butchered in Montrose and frozen. Wait till you taste it with Lisa's special Mornay sauce."

A short time later, they were all seated at a pine log table Marquez had built inside the glassed-in porch, enjoying the elk steaks coated with Lisa's delicious sauce. Creamed spinach, baked potatoes, and a big bowl of salad enhanced the elk. Marquez had asked Pat and Dirk not to say too much about their harrowing experience. He didn't want to upset his wife any more than he had to. She had suffered enough during her agonizing wait until the word had come that he had exited the mine and was safe and sound. They had treated the ordeal lightly, omitting any reference to the killers and telling her that Ambrose was meeting friends and couldn't make it for dinner.

Despite the fact that they acted as if they had returned from a walk in the park, Lisa knew better, but she said nothing. After dinner, Pat helped her clear the table and returned, while Lisa busily fed her young daughters and made coffee before bringing out a carrot cake.

"Excuse me for a moment," said Pitt. He walked into the house and said a few words to Lisa before rejoining Pat and Marquez at the table.

Satisfied that his wife was out of earshot, Marquez stared directly at Pitt and said, "I can't accept your theory about Dr. Ambrose. I feel certain that he was murdered soon after we left him."

"I agree with Luis," said Pat. "To suggest that Tom was anything but a respected scientist is ridiculous."

"Had you ever met Ambrose before today?" asked Pitt.

She shook her head. "No, but I know him by reputation."

"But you've never seen him."

"No."

"Then how do you know whether the man we knew as Tom Ambrose wasn't an impostor?"

"All right," said Marquez. "Suppose he was a fake and working with those crazy bikers. How do you explain that fact that he would have surely drowned if you hadn't showed up?"

"That's right," Pat interjected quietly. "There's no way he'd be tied to a criminal conspiracy if the killers tried to murder him, too."

"His fellow assassins screwed up." There was a cold certainty in Pitt's voice. "They may have been demolitions experts, but not being professional hardrock miners like Luis, they set off an explosive charge too powerful for the job. Instead of merely causing a cave-in and blocking off the tunnel, they collapsed the rock holding back an underground river, diverting it into the lower levels of the mine. A miscalculation that fouled up their plans. The shaft and the chamber with the skull flooded before they could detour around the cave-in on their bikes to rescue their chief."

Marquez stared up at the mountain peaks surrounding Telluride that were outlined by the light of the evening stars. "Why cause the tunnel roof to collapse? What did they gain from that?"

"The perfect murder," answered Pitt. "They meant to kill the two of you by beating your brains in with rocks. Then they would have buried your bodies in the debris from the cave-in. When and if your remains were ever found, your deaths would be written off as a mining accident."

"Why kill us?" Pat asked incredulously. "For what purpose?"

"Because you posed a threat."

"Luis and I a threat?" She looked confused. "To whom?"

"To a well-financed, well-organized secret interest who didn't want the discovery of the chamber with the black skull to become public knowledge."

"Why would anyone want to cover up a major archaeological discovery?" said Pat, completely off balance.

Pitt turned up the Palms of his hands in a helpless gesture. "That's where conjecture stops. But I'm willing to bet the farm that this is not an isolated incident. That a trail of bodies leads to other fords of this magnitude."

"The only other archaeological project I can think of that is surrounded in this kind of mystery was an expedition led by Dr. Jeffrey Taffet from Arizona State University. He and several students died while exploring a cave on the northern slope of Mount Lascar in Chile."

"What was the cause of their deaths?" asked Marquez.

"They were found frozen to death," answered Pat. "Which was very peculiar, according to the rescue team who found the bodies. The weather had been perfect, without storms, and temperatures were barely below freezing. An investigation turned up no reason for Taffet and his students to have succumbed to hypothermia."

"What was of archaeological interest in the cave?" Pitt prompted.

"No one knows for sure. A pair of amateur mountain climbers from New York, both successful tax attorneys, discovered and explored the cave while descending from the summit of the mountain. They described ancient artifacts neatly placed about inside, shortly before they were killed."

Pitt stared at her. "They died, too?"

"Their private plane crashed on takeoff from the airport at Santiago for the flight home."

"The mystery deepens."

"Subsequent expeditions to the cave found nothing inside," Pat continued. "Either the attorneys exaggerated what they saw-"

"Or someone cleaned out the artifacts," Pitt finished.

"I wonder if the attorneys found a black skull," mused Marquez.

Pat shrugged. "No one will ever know."

"Did you manage to salvage your notes from the chamber?" Marquez asked Pat.

"The pages were soaked during our swim through the mine, but once I dried them with my hair dryer, they became quite readable. And if you have any questions about the meaning of the inscriptions, you can forget them. The symbols are from no known form of writing I've ever seen."

"I would think that written symbols cross over cultures, ancient and modern- that they would have similar markings," said Pitt thoughtfully.

"Not necessarily. There are many ancient inscriptions that stand alone without parallel symbols. Believe me when I say the signs on the walls in the chamber of the black skull are unique."

"Any chance they might be a deception?"

"I won't know until I have a chance to study them in depth."

"Take it from me," Marquez stated emphatically, "no one had entered that chamber before me in a long time. The surrounding rock showed no signs of recent digging."

Pat brushed her long red hair from her eyes. "The puzzle is who built it and why."

"And when," Pitt threw in. "Somehow the chamber and the killers are tied together."

A sudden breeze whistled up the canyon, rattling the windows of the solarium. Pat shivered. "The evening is getting cool. I think I'll get my coat."

Marquez turned toward the kitchen. "I wonder where Lisa is with the coffee and cake-"

His voice broke off as Pitt suddenly leaped to his feet. In one convulsive movement, he shoved the miner under the log table, then seized Pat and threw her to the wooden floor, covering her body with his own. Some alien wisp of movement in the shadows beside the house had tweaked the acute sense of menace that had been honed in him over the years. In the next instant, two explosions of gunfire burst from the shadows outside, coming so close together, they sounded as one.