sheer blackness of the water. After less than five minutes, he reached the midway point. He adjusted his face mask, ducked his head under the water and began breathing through the snorkel. Another four minutes put him a hundred yards from the retreat's boat dock. The work boat was still gone, but the yacht still tugged at her mooring lines.

This was as far as he dared go on the surface. He spit out the snorkel and clamped his teeth on the mouthpiece to his breathing regulator. Accompanied by the hiss of his exhaust, he tilted the Stingray downward and dropped into the depths, leveling out about ten feet above the bottom, hovering motionless for a few moments while adding air to his dry suit to achieve neutral buoyancy, then snorting and clearing his ears from the increase of water pressure. The lights of the retreat cast a translucent glow beneath the water. Pitt felt as if the propulsion vehicle was pulling him through liquid glass coated in an eerie green. He averted his eyes from the graveyard below as visibility increased from practically nil to thirty feet the closer Pitt approached the dock. Fortunately, he could not be discerned from above because the reflection on the surface of the water caused a glare that prevented all but a very limited view of the depths.

He decreased the Stingray's speed and moved slowly under the keel of the yacht. The hull was clean and free of any marine growth. Finding nothing of interest except a school of small fish, Pitt cautiously approached the floating log hut from which the guards on their Chinese-built personal watercraft had burst the previous afternoon. His heartbeat increased as he measured his opportunities of escape if he was discovered. They flat didn't exist. A swimmer stood little chance of outrunning a pair of personal watercraft with a top speed of thirty miles per hour. Unless they were prepared to come after him underwater, all they had to do was outwait him until he exhausted his air supply.

He had to be very careful. There would be no light reflection on the surface inside the hut. To anyone sitting in a darkened room over calm water it would be like staring into the depths from a glass-bottomed boat. He yearned for a passing school of fish to hide among, but none appeared. This is madness, he thought. If he had an ounce of gray matter he'd make his getaway while he was yet unseen, swim back across the lake to the cabin and call the police. That's what any sane man would have done.

Pitt felt no fear but a degree of trepidation at not knowing whether he would find himself looking up into the muzzle of an automatic rifle. But he was determined to find out why all those people had died, and he had to find out now or there would never be another chance. He drew the air gun from its holster and held it vertically, barrel and barb pointing upward. Slowly, so no sudden movement would be noticed, he released the speed switch to the Stingray's twin motors and gently kicked his fins until he eased under the floats of the hut. He peered upward through the water inside the boathouse, holding his breath so that his air bubbles would not advertise his arrival. The view looking up from less than two feet underwater was similar to gazing through six inches of gossamer.

Except for the two watercraft, the interior appeared dark and empty. He reset the dive light on his head, surfaced and beamed it around the floating hut. The fiberglass hulls of the watercraft were set snugly between two docks that were open at the front. Once the door of the hut was thrown aside, their riders could speed directly onto the lake. He reached out, rapped the door with his fist and received a hollow sound. The logs were fake, painted on a thin sheet of plywood. With no small amount of effort, Pitt hoisted himself and his equipment onto one of the docks. He removed his air tanks, fins and weight belt, and parked them in a watercraft. The Stingray, because it was slightly buoyant, he allowed to drift beside the dock.

Gripping the air gun, he moved quietly toward a closed door at the rear of the hut. He lightly laid his fingers on the latch, slowly turned it and eased the door open half an inch, just enough to see that it opened onto a passageway that led down a long ramp. Pitt moved like a wraith -at least he wanted to move like a wraith. His every footstep in the rubber dive boots sounded to him like the beat of a bass drum, when actually they touched the concrete floor without so much as a whisper. The ramp dropped into a narrow concrete passageway barely wide enough for Pitt's shoulders. Lit by overhead recessed lights, it appeared to lead under the water toward the shoreline. It was a reasonable assumption that the passageway extended from the boathouse to a basement below the main building. That was why it took so long for the guards who rode the watercraft to respond after the AUV was sighted. Unable to ride even a bicycle through the narrow passageway, they had to sprint nearly two hundred yards.

A quick look to see if his movements were covered by surveillance cameras-he saw none-and Pitt cautiously began to advance along the tightly spaced walls, having to turn slightly sideways to pass through. He cursed the contractor who poured the concrete with the smaller Chinese physique in mind. The passage ended at another ramp that rose and widened through an archway. Beyond, a corridor stretched off into the distance with doors on either side.

He moved to the first door that was slightly ajar. A glance from a wary eye through the crack revealed a low bed occupied by a sleeping man wearing a skullcap. There was a closet with hanging clothes, a dresser with several small drawers, a nightstand and lamp. One rack on a wall held a variety of weapons: a sniper's rifle with a scope, two different automatic rifles and four automatic pistols of different calibers. Pitt quickly realized that he had walked into the lions' den. This was the living quarters for the security guards.

Voices came from another room farther down the corridor along with the pungent aroma of incense. He dropped prone and sneaked a peek across the threshold with half an eye and nose he hoped would not be as obvious low to the floor. Four Asians were seated around a table playing dominoes. Their conversation was unintelligible to Pitt. To his untrained ear the Mandarin dialect sounded like a fast pitch by a used-car dealer in a television commercial that was speeded up and played backward. Through the doors of other rooms he could hear the strange, twangy sounds that Orientals call music.

It seemed like a good idea to move out of the area quickly. There was no way of telling when one of the unsuspecting guards might happen to step into the corridor and demand to know why a Caucasian was slinking around outside his bedroom. Pitt moved on until he found an iron spiral staircase. Still no shouts of discovery, no gunshots, no sirens or alarm bells. He was more than happy to find that Shang's security people were less concerned about trespassers on the inside than on the outside.

The staircase rose past two levels that were empty, great open areas with no interior walls. They appeared to Pitt as if the contractor and his workers had walked off the job before it was completed. He finally reached the top landing and stopped at a massive steel door that looked like it came off a bank vault. There was no time or combination lock, only a thick horizontal handle. He stood there for a solid minute, listening intently but hearing nothing while pushing down on the handle with firm but gentle pressure. Sweat poured from his body beneath the dry suit. Swimming back to the cabin in the frigid water of the lake began to sound good to him. He decided that one quick look inside the main house and he was out of there.

The shafts slid smoothly and silently out of their slots. Pitt hesitated for several moments before he began, ever so delicately at first, to pull open the massive door. Soon he had to exert most of his strength until it cracked enough to see beyond. What he saw was another door, but this one had bars. No cat burglar could have been half as surprised to find the house he came to rob of precious jewels and valuables was a maximum-security prison.

This was no elegant estate built by a man with unusual taste in architecture. This had no correlation to an estate at all. The entire interior of Shang's huge house was a cell block straight out of Alcatraz. The revelation struck Pitt like a blow to the head by a meteor. The retreat built to entertain Shang's clients and business associates was a facade, he realized, a damned facade. The maid who played at making up rooms with no furniture, the two golfers who played for

all eternity -they were all frosted figures on a cake. The security that was carried to extremes was designed to keep captives in rather than intruders out. It now became obvious that the copper-tinted solar glass panes were backed by reinforced concrete walls.

Three tiers of jail cells faced an open square with a cage mounted on columns in the center. Inside the cage, two guards in gray, unmarked uniforms monitored a bank of video screens. The upper walkways that passed by the cells were shielded from the open square by mesh screens. The cell doors were solid except for peepholes barely large enough to insert a small plate of food and a cup of water. The most hardened incarcerated criminal would have had a tough time figuring an escape route out of this place.

There was no way for Pitt to tell how many poor souls were locked behind the doors. Nor could he guess who they were or what offense they had committed against Shang. Recalling the AUV's video of the sickening spectacle on the lake bed, he began to grasp that instead of staring at a penal colony he was staring at one huge death row.

Pitt felt a cold chill, but sweat was trickling down his face in streams. He had overstayed his welcome. It was time to head home and blow the whistle. Very carefully, he pushed the steel door closed and locked it in place. Lucky, lucky, he thought. Only the inside door with the bars was wired to sound an alarm when opened without permission by the guards at the security monitors. He was on the fourth step going down when he heard footsteps coming up.

There were two of them, no doubt a change of a shift for the men monitoring the video surveillance around the outer grounds and inside the prison cells. Neither had call to be apprehensive or suspicious of intruders. They casually moved up the stairs chatting to each other, and due to the human habit of watching one's feet when climbing a staircase, neither looked up and spied Pitt. Their only weapons were automatic pistols firmly clipped in their holsters.

Pitt had to move fast if he wanted the advantage of surprise, and he used it to the hilt. Foolhardy or not, he rushed down the stairs and leaped, crashing into the lead guard before he literally knew what hit him and throwing him backward into his friend.

Accustomed to cowering and frightened captives, the two Chinese guards were petrified with shock at being attacked by a reckless crazy man in a rubber suit whose body was considerably larger than either of theirs. Both men, caught off balance, stumbled and fell backward, arms and legs flailing, locked together back to chest. Pitt piled on the man on the top and rode them down the steps to the second landing before they all crumpled against a railing. The bottom man struck his head on a step and was immediately knocked unconscious. His friend, less injured but stunned with surprise, snatched feverishly at his holstered automatic.

Pitt could have killed him, could have killed them both, by shooting a pair of barbs through their heads. But he settled for gripping the air gun by the barrel and clubbing the guard on the side of the head with the butt. He didn't doubt for an instant that if their positions were reversed, they'd have had no misgivings whatsoever about blowing his brains out.

He dragged them into the vacant second level and propped them against the far wall in the shadows. He tore off their uniforms and ripped them into strips. Then he bound their hands and legs, and gagged them. If, as he suspected, they were on their way to work, they'd be missed in less than five or ten minutes at the most. Once they were found knocked unconscious and bound with shreds of their uniforms, all hell would erupt when an intrusion was reported to Shang or his murder advisory board. Once they became aware their security had been penetrated by an unknown force, there was no second-guessing the consequences. He didn't want to think about what might happen to the unfortunates still locked in the cells if it was decided all evidence to whatever was going on had to be destroyed and all eyewitnesses killed. If the bodies on the bottom of the lake were any indication, whatever this bunch of slime lacked, it certainly wasn't a willingness to murder by the numbers.

Pitt crept back through the corridor of the guards' living quarters with the finesse of Don Juan flitting out of a lady's bedroom. The luck he had of not being seen going in carried with him going out. He reached the passageway to the boathouse and hurried through as best he could without scraping the shoulders of his dry suit to shreds. Not in the mood for an exciting pursuit by incensed Chinese with lethal weapons, he briefly considered working over the motors of the water-craft, but thought better of wasting the time. If they couldn't find the AUV in broad daylight, they would never find him thirty feet underwater in the dark.

After hurriedly putting on his dive gear, he dropped into the water, swam around the dock and retrieved the Stingray. Pitt hadn't traveled a hundred yards along the lake bed when he heard the throb of an engine exhaust and the beat of propellers from a boat coming out of the darkness in the distance. The sound carried through the water faster than the air, making it seem as if the boat was almost on top of him when in fact it was just coming off the river outlet onto the lake. Inclining the Stingray, he let its thrust pull him to the surface. He spotted the boat as it moved out of the shadows and became illuminated under the lights from shore. He identified the approaching vessel as the black catamaran he'd observed the day before.

He figured that unless one of the boat's crew ate a bushel of carrots every day and took large doses of vitamin A for acute night vision, their chances of picking out a nearly invisible head on dark waters were unlikely. Then suddenly, the boat's motor died to an idle and it drifted to a stop not fifty feet away.

Pitt should have ignored the boat and moved on. There was still plenty of juice left in the Stingray's batteries to take him back to the cabin. He should have moved on, having seen more than he was ever meant to see. Law-enforcement authorities had to be notified quickly before any further harm came to the unknown human beings imprisoned inside the retreat. He was cold and exhausted and looked forward to a shot of tequila and a chair in front of a warm fire. He should have listened to an inner voice telling him to get the hell away from Orion Lake while the getting was still good. His inner voice might as well have pleaded with his sinus passages for all the good it did.

Some unfathomable fascination attracted him to the eerie-looking catamaran. There was something sinister about its appearance in the night. No one walked the decks, no lights showed anywhere.

Downright diabolic, he thought. A strange, indescribable malignance seem to vent from its decks. Then it began to dawn on Pitt that this just might be the ferry that transported dead souls across the River Styx. He rolled beneath the surface and aimed the Stingray in a downward and then upward arc that would bring him beneath the twin hulls of the mysterious vessel.

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