'Since then,' Sandwell continued, disregarding him, 'we've found three more capsules just like it. They have detonators designed to be triggered by a coded radio command. Once placed, they can only be neutralized with the proper signal. Tamper with it, and you saw what happens. And so we leave them untouched. Here's a video of the most recent cylinder. It was discovered five days ago.'

This time the players were dressed in biochem suits. They moved with the slowness of astronauts in zero gravity. The dateline was different. It said ClipGal/Rail/09-01/0732:12. The camera angle shifted to a fracture in the cave wall. One of the suited troops started to insert a shiny stick into the crack. It was a dental mirror, January saw.

The next angle focused on an image in the mirror. 'This is the backside of one of the capsules,' Sandwell said.

The lettering was complete this time, though upside down. There was a tiny bar code, and an identification in English script. Sandwell froze the image. 'Right side up,' he ordered. The camera angle pivoted. SP-9, the lettering said, followed by USDoD.

'It's one of ours?' a voice asked.

'The "SP" designates a synthetic prion, manufactured in the laboratory. Nine is the generation number.'

'Is that supposed to be good news or bad news?' someone said. 'The hadals aren't manufacturing the contagion that's killing us. We are.'

'The Prion-9 model has an accelerant built in. On contact with the skin, it colonizes almost instantly. The lab director compared it to a supersonic black plague.' Sandwell paused. 'Prion-9 was tailored for the theater in case things got out of hand down below. But once they built the prion, it was decided that nothing could get so out of hand to ever use it. Simply put, it's too deadly to be deployed. Because it reproduces, small amounts have the potential to expand and fill an environmental niche. In this case, that niche is the entire subplanet.'

A hand closed on January's arm with the force of a trap. The pain of Thomas's grip traveled up her bone. He let go. 'I'm sorry,' he whispered, and took his hand away.

January knew better than to interrupt a military briefing. She did it anyway. 'And what happens when this prion fills its niche and decides to jump to the next niche? What about our world?'

'Excellent question, Senator. There is some good news with the bad. Prion-9 was developed for use in the subplanet exclusively. It only lives - and only kills - in darkness. It dies in sunlight.'

'In other words, it can't jump its niche. That's the theory?' She let her skepticism hang.

Sandwell added, 'One other thing. The synthetic prion has been tested on captive hadals. Once exposed, they die twice as fast as we do.'

'Now there's an edge for you,' someone snorted. 'Nine-tenths of a second.'

Captive hadals? Tests? January had never heard of these things.

'Last of all,' Sandwell said, 'all remaining stocks of this generation have been destroyed.'

'Are there other generations?'

'That's cla.s.sified. Prion-9 was going to be destroyed anyway. The order arrived just days after the theft. Except for the contraband cylinders already in the subplanet, there are no more.'

A question came from the dark room. 'How did the hadals get their hands on our ordnance, General?'

'It's not the hadals who planted the prion in our ClipGal corridor,' Sandwell snapped. 'We have proof now. It was one of us.'

The video screen came on again. January was certain he was replaying the first tape. It looked to be the same black tunnel, disgorging the same disembodied heat signatures. The hot green amoebas became bipedal. She checked the dateline. The images came from Line station number 1492. But the date was different. It read 06/18. This video had been shot two weeks earlier than the SEAL patrol.

'Who are these people?' a voice asked.

The heat signatures took on distinct faces. A dozen became two dozen, all strung out. They weren't soldiers. But with their night gla.s.ses on, it was impossible to say exactly who or what they were. The first array of tunnel lights automatically engaged. And suddenly the figures on screen could be seen yelling happily and stripping their gla.s.ses off and generally acting like civilians on a holiday.

Their Helios uniforms were dirty, but not tattered or badly worn. January made a quick calculation. At this point, the expedition had been in its second month of trekking.

'Look,' she whispered to Thomas.

It was Ali. She had a pack on and looked healthy, if thin, and better fit than some of the men. Her smile was a thing of beauty. She pa.s.sed the wall camera with no idea that it was taping her.

Without turning her head, January noticed a change in the soldiers around her. In some way, Ali's smile testified to their n.o.bility.

'The Helios expedition,' Sandwell said for those who did not know.

More and more people filled the screen. Sandwell let his commanders appreciate the whole potpourri. Someone said, 'You mean to say one of them planted the cylinders?'

Again Sandwell set them straight. 'I repeat, it was one of us.' He paused. 'Not them. Us. One of you.'

January fastened upon Ali's image. On screen, the young woman knelt by her pack and unrolled a thin sleeping pad on the stone and shared a candy with a friend. Her small communion with her neighbors was endearing.

Ali finished her preparations, then sat on her pad and opened a foil packet with a folded washcloth and cleaned her face and neck. Finally she folded her hands and exhaled. You could not mistake her contentment. At the end of her day, she was satisfied with her lot. She was happy.

Ali glanced up, and January thought she was praying. But Ali was looking at the lights in the tunnel ceiling. It verged on worship. January felt touched and appalled at the same time. For Ali loved the light. It was that simple. She loved the light. And yet she had given it up. All for what? For me, thought January.

'I know that son of a b.i.t.c.h.' It was one of the ClipGal commanders speaking.

At center screen, a lean mercenary was issuing orders to three other armed men. 'His name's Walker,' the commander said. 'Ex-Air Force. Jockeyed F-16s, then quit to go into business for himself. He got a bunch of Baptists killed on that colony venture south of the Baja structure. The survivors sued him for breach of contract. Somehow he ended up in my neighborhood. I heard Helios was hiring muscle. They got themselves a cl.u.s.ter-f.u.c.k.'

Sandwell let the tape run another minute without comment. Then he said, 'It's not Walker who planted the prion capsules.' He froze the image. 'It's this man.'

Thomas gave a start, all but imperceptible. January felt the shock of recognition. She looked at his face quizzically, and his eyes skipped to hers. He shook his head. Wrong man. She returned her attention to the image on screen, searching her memory. The vandalized figure was no one she knew.

'You're mistaken,' a soldier stated matter-of-factly from the audience. January knew that voice.

'Major Branch?' Sandwell said. 'Is that you, Elias?'

Branch stood up, blocking part of the screen. His silhouette was thick and warped and primitive. 'Your information is incorrect. Sir.'

'You do recognize him then?'

The image frozen on screen was a three-quarters profile, tattooed, hair trimmed with a knife. Again January sensed Thomas's recoil. A click of teeth, a shift in breathing. He was staring at the screen. 'Do we know this man?' she whispered. Thomas lifted his fingers: No.

'You've made a mistake,' Branch repeated.

'I wish we had,' said Sandwell. 'He's gone rogue, Elias. That's the fact.'

'No sir,' Branch declared.

'It's our own fault,' Sandwell said. 'We took him in. The Army gave him sanctuary. We presumed he had returned to us. But it's very possible he never quit identifying with the hadals who had captured him. You've all heard of the Stockholm syndrome.'

Branch scoffed. At his superior officer. 'You're saying he's working for the devil?'

'I'm saying he appears to be a psychological refugee. He's trapped between two species, preying on each. The way I look at it, he's killing my men. And taking aim at the whole subplanet.'

'Him,' breathed January. Now the shock was hers. 'Thomas, he's the one Ali wrote us about just before leaving Point Z-3. The Helios scout.'

'Who?' asked Thomas.

January drew the name from her mental bank. 'Ike. Crockett,' she whispered. 'A recapture. He escaped from the hadals. Ali said she was hoping to interview him, get his remembrances of hadal life, enlist his knowledge. What have I gotten her involved with?'

'Judging by his work so far,' Sandwell continued, 'Crockett is attempting to lay a belt of contagion along the entire sub-Pacific equator. With one signal he can trigger a chain reaction that will wipe out every living thing in the interior, human, hadal, and otherwise.'

'Give me your proof,' Branch insisted stubbornly. 'Show me one clip or one picture of Ike planting CBs.' January heard heartbreak mixed in with his defiance. Branch had some connection with this character on screen.

'We have no pictures,' Sandwell said. 'But we've retraced the original batch of stolen Prion-9. It was stolen from our West Virginia chemical weapons depot. The theft occurred the same week that Crockett visited Washington, D.C. The same week he was to face a court-martial and a dishonorable discharge, and then fled. Now four of those cylinders have been discovered in the very same corridor he's guiding the Helios expedition through.'

'If the contagion goes off, he dies too,' said Branch. 'That's not Ike. He wouldn't kill himself. Anyone who knows him can tell you. He's a survivor.'

'In fact, that's our clue,' Sandwell said. 'Your protege had himself immunized.'

There was silence.

'We interviewed the physician who administered the vaccine,' Sandwell went on. 'He remembered the incident, and for good reason. Only one man has ever been immunized against Prion-9.'

A photograph flashed on the screen. It showed a medical release form. Sandwell let them have a minute with it. There was a doctor's name and address at the top. And at the bottom, a plain signature. Sandwell read it aloud: 'Dwight D. Crockett.'

's.h.i.t,' grunted one of the commanders.

Branch was stubborn in his loyalty. 'I dispute your proof.'

'I know this is difficult,' Sandwell said to him.

Men stirred uneasily, January noticed. Later she would learn that Ike had taught many of them, saved some of them.

'It's imperative that we find this traitor,' Sandwell told them. 'Ike has just made himself the most wanted man on earth.'

January raised her voice. 'Let me understand,' she said. 'The only person immune to this plague, today, is the man who is planting it?'

'Affirmative, Senator,' Sandwell said. 'But not for long. In order to contain the prion release, we've closed the entire ClipGal corridor with explosives. We're evacuating the subplanet within a two-hundred-mile radius, including Nazca City. No one goes back in again until they get vaccinated. We start with you, gentlemen. We have medics waiting for you in the next room. Senator, and Father Thomas, you're both welcome to be vaccinated too.'

Before January could decline, Thomas accepted. He glanced at her. 'In case,' he said.

A map filled the screen. It zoomed in on a vein within the earth. 'This is the Helios expedition's projected trajectory,' the general continued. 'There's probably no way we can catch them from behind, meaning we have to intercept them from the side or the front. The problem is, we know where they've been, but not exactly where they're going.

'The Helios cartel has agreed to share information about the expedition's projected course. Over the next months, we'll be working closely with their mapping department to try to pinpoint the explorers. Meanwhile, we hunt.'

'We're going to commit all possible a.s.sets. I want squads sent out. Exit points covered. We'll flush him out. We'll lay traps. We'll wait for him. And when he's located, you're to shoot him dead. On sight. That order comes from the top. I repeat, kill on sight. Before this renegade can kill us.'

Sandwell faced them. 'Now is the time to ask yourselves, is there any man here who cannot deal with the mission as described?'

He was asking one man alone. They all knew it. Their silence waited for Branch to recuse himself. He did not.

New Guinea The phone call at 0330 woke Branch in his berth. He slept little anyway. Two days had pa.s.sed since the commanders had returned to their bases and begun harrowing the depths to find Ike. Branch, however, was a.s.signed to mission control at SouthPac's New Guinea headquarters. It had been dressed up as a humanitarian gesture, but was fundamentally a way to neutralize him. They wanted Branch's insights into their prey, but did not trust him to kill Ike. He didn't blame them.

'Major Branch,' a voice said on the phone. 'This is Father Thomas.'

Ever since the briefing, Branch had been expecting a call from January. His connection was with her, not with her Jesuit confidant. He'd been surprised when the senator brought the man to their Antarctic meeting, and was not pleased to hear his voice. 'How did you find me?' he asked.

'January.'

'This probably isn't the best phone line to be using,' Branch rankled.

Thomas disregarded him. 'I have information about your soldier Crockett.'

Branch waited.

'Someone is using our friend.'

Our friend? thought Branch.

'I've just returned from visiting the physician who administered the vaccine.'

Branch listened. Hard.

'I showed him a photo of Mr Crockett.'

Branch screwed the phone tighter against his ear.

'I think we can agree he has a rather distinctive look. But the physician had never seen Crockett in his life. Someone forged his signature. Someone posed as him.'

Branch eased his grip. 'Is it Walker then?' That had been his first suspicion.

'No,' said Thomas. 'I showed him Walker's photo. And photos of each of his hired gunmen. The physician was adamant. It was none of them.'

'Then who?'

'I don't know. But something isn't right here. I'm trying to obtain photos of all the expedition members to show him. The Helios corporation is proving less than accommodating. In fact, the Helios representative told me there's officially no such expedition.'

Branch made himself sit on the edge of the fibergla.s.s bed rack. It was difficult to be calm. What was this priest's game? Why was he playing detective with an Army physician? And placing phone calls in the middle of the night like this, trumpeting Ike's innocence? 'I don't have photos, either,' said Branch.

'It occurred to me that another source of images might be that video General Sandwell played for us. It seemed to have a lot of faces.'

So that was it. 'You want me to get it for you.'

'Perhaps the physician could pick his man from the crowd.'

'Then ask Sandwell.'

'I have. He's no more forthcoming than the corporation itself. In fact, I suspect he's something other than what he pretends to be.'

'I'll see what I can do,' Branch said. He didn't commit himself to the theory.

'Is there any chance of stopping the search for Crockett, or at least stalling it?'

'Negative. Hunter-killer teams have been inserted. They're going deep, a month each. Beyond recall.'

'Then we need to move quickly. Send that video to the senator's office.'