Two more quick bursts. "I can try," said Reggie.

That's all any of us can do right now.

"Searching."

Margot sat back to wait. She listened to the hum of the ship and the sound of her own breathing. No other sounds. She couldn't hear Nick and Jean down in engineering. She couldn't hear Tom anywhere.

Worry spiked in the back of her mind. What if he was taking the quick way out? What if he was angryenough to take Nick out instead?

No, she shook her head. Tom's just on edge. They're friends.

Were they? She remembered the stranger looking out of Tom's eyes. Would that stranger recognize Nick? Would Nick recognize him? She glanced nervously over her shoulder. No one floated in the connector. She looked back at the screen. Reggie had a list up-names, orbital parameters, current locations, sizes, with an option to display orbital plots and position relative to the Forty-Niner.

Highlighted at the top was Comet Kowalski-Rice.

Sounds like a breakfast cereal. Margot glanced over her shoulder again. The connector was still empty. The ship was still silent.

Kowalski-Rice was a periodic comet, with a nucleus estimated to be three kilometers long and between one and three kilometers wide. It had pa.s.sed its aphelion and was headed back toward the Sun. Right now it was 2.9 million kilometers from the Forty-Niner, but it was getting closer. Margot brought up the orbital plot and did a quick calculation.

We burn fifty...OK say sixty to be on the safe side, percent of the remaining propellant we can bring our orbit within seven hundred-fifty kilometers of the comet. Take about...She ran the equations in her head. She could double check them with Reggie or Nick, whoever turned out to be more reliable. Bring us there in about a hundred and fifty-nine hours, with the comet going approximately two kilometers per second relative to the ship. This could work. This could work.

Silence, except for the steady hum of the ship and her own breathing.

Margot swore. This is no good. "Reggie? Do you know where Tom is?"

"Tom Merritt is in the sick bay."

"No!" Margot yanked both feet up and kicked off the console. "Nick! Jean!" she shouted. "Sick bay! Now!"

She reached sick bay first. She wrenched the wheel around and threw the hatch open. A little red sphere drifted out toward her face. Margot swatted at it reflexively and it broke against her hand, scattering dark red motes in a dozen directions.

Tom had fastened himself to the examining table and sliced his throat. Clouds of burgundy bubbles rose from his neck, knocking against a pair of scissors and sending them spinning.

"Tom!" Margot dove forward and pressed her fingers against his wound. Panting, she tried to think back to her emergency medical training. Dark red, not bright, oozing, not spurting, missed the carotid artery, cut a bunch of veins...Tom, you idiot, you're so far gone you can't even kill yourself right.

Events blurred. It seemed like Nick, Jean and Reggie were all shouting at once. A pad got shoved into her hand to help staunch the blood. The table was tilted to elevate his head. Reggie droned on clear and concise directions for covering the long, thin wound with layered sealants. Nick's and Jean's hands shook as they worked. Blood and tears stung Margot's eyes.

When they were done, Tom was still strapped to the table, unconscious and dead white, but breathing. The medical ex-system was obviously still working. Reggie had no problem reading from the various pads and probes they had stuck to him. It was giving him good odds on survival, despite the blood loss.

"Let's get out of here," said Nick. "We can vacuum this up when we've had a chance to catch our breath."

Jean didn't argue, she just headed for the hatch. Margot had the distinct feeling she wanted to crawl into a corner and be quietly sick.

Margot followed Nick and Jean out and swung the hatch shut. She wanted to be able to talk without getting a mouthful of blood.

"G.o.d," Nick ran both hands through his hair. "I cannot believe it, I cannot believe he did this."

Unfamiliar indecision showed on his face. Margot turned her gaze away. Another stranger. Just one more. Like Tom, like the others.

No! she wanted to scream. Not you. I know you! You recommended me for this mission. You have a great poker face and you sing country-western so loud in the shower the soundproofingcan't keep it in! You keep all the stats on your kids' sports teams displayed as the default screen on your handheld! Your wife's the only woman you've ever been with! I know Nicholas Alexander Deale!

But she did not know the person torn with weariness, anger and doubt who looked out of Nick's eyes. The one who might be a liar on a scale she'd never imagined. How long before that stranger took Nick completely over?

Margot looked at Jean. Blood splotched her face, hands, hair and coveralls. Fear haunted her bruised-looking eyes. Fear brought the stranger. Jean would go next. The stranger would have them all.

Tom was right. They were all dead. Only the strangers and Margot Rusch lived.

"What is it, Margot?" asked Nick.

What do I say? Which "it" do I pick? Who let the stranger into Tom? Me or you? She licked her lips. Well, it does not get me. It does not get me.

"Nothing." Margot grabbed a handhold and pulled herself toward the command center. "I'm going to find that comet."

After all, that was what the strangers wanted her to do. She had to do what they said. If she didn't...look what they did to Tom. Who knew what they'd do to her?

They do not get me.

"Here it comes, Margot," the voice that used to be Nick's crackled through her helmet's intercom.

Margot turned in her straps, and there it came. Actually, Kowalski-Rice had been visible to the naked eye for the past two days. The comet was ungainly and beautiful at the same time. A dirty s...o...b..ll tumbling through the darkness surrounded by a sparkling veil fit for an angel's bride. It was huge-a living, shining island, coal black and ice white. Margot's hands tightened on the twin joy sticks that were the directional control for the explorer.

They had planned the maneuver out so carefully and modeled it so thoroughly. She had to give the strangers who walked as Nick and Jean credit. They were very good at what they did.

Jean's stranger had cobbled together the "harpoon" from drill shafts, explosives and hope. The grappling shaft had a timed explosive mounted on it and a solid propellant sh.e.l.l around it. When Margot pulled the pin, the propellant would ignite and burn for one minute to drive the harpoon to the comet. At one minute ten seconds the explosive would blow, driving the barbed head deep into the comet's hide. It had taken all of them to unwind and detach the mag sail cable from the drum and then rewind it, as if they were reeling in a gigantic fishing line. The very end of that cable had been welded to the harpoon using all the vacuum glue and tape Jean's stranger could lay her hands on. Jean's stranger had spent hours out on the hull, readjusting the tension on the cable drum so the pay out would be smooth.

Margot would launch the harpoon into the comet. The cable would pay out. Once the harpoon struck, the friction of the cable unwinding against the barrel would accelerate the Forty-Niner, and Margot in the explorer, which was tethered to the Forty-Niner by the cables that used to be the shroud lines for the mag sail. The more the cable unwound, the faster the ships would accelerate. Finally, the cable would run out. The comet would shoot forward with its leash trailing behind it, and the Forty-Niner and the strangers would fly free toward an areobraking rendezvous with Mars, and a rescue by NASA.

At least, that's what they said would happen. They might be lying. There was no way to tell. But if Margot refused to go along, they'd probably just kill her. She had to play. She had to act like she believed they were who they said they were. It was her only chance.

She tried to tell herself it didn't matter. She tried to believe what she'd told Tom, who they still, miraculously, let live, that it didn't matter who'd come up with the idea-aliens, the strangers, it didn't matter. If Nick and Jean, and Tracy and Ed, and Paul and even Tom finally were overcome by the strangers, it didn't really matter. What mattered was getting home. If she could get home, she could warn everyone.

But first she had to get home. She, Margot Rusch, had to get home.

"Better get ready, Margot," said Nick's stranger. "It's all on you."So it is. And you hate that, don't you? I could mess up all your plans and you know it, but you can't get me. Not out here you can't.

Margot squeezed the stick, goosing the engine. Silently, her little frame ship angled to starboard, sliding gingerly closer to the wandering mountain of coal black ice and stone. Behind her, the three shining silver tethers that attached the explorer to the Forty-Niner paid out into the darkness.

She gave the comet's path a wide berth, but not so wide that she couldn't see how it lumbered, turning and shuddering as sparkling jets shot off its pocked hide.

I can do this. How many asteroids did we skirt? They were all falling too.

But not like this. She imagined the comet hissing and rumbling as it dashed forward. They're making me do this. They don't care if I die.

Black specks dusted her visor. She wiped at them. She glanced behind to see that the tethers were moving smoothly. The comet was almost in front of her. Black ice, black stone and the sparkling white coma surmounted the darkness.

Suddenly, the rover shuddered and Margot jerked in her straps. A stone careened off the frame ship and shot past her head.

That was a warning shot. That was them...No, no, they can't get me out here, but the comet can. Keep your mind on the comet, Margot. Don't think about them.

The Forty-Niner was below and behind her now. The comet was receding. The coma filled the vacuum, shining like a snow blowing in the sunlight. Margot pitched the rover up and around, until the comet was flying away from her, but she was not in the thick of its tail.

For a moment, she was nothing but a pilot and she smiled.

Perfect deflection shot. Fire this baby right up its tail-pipe.

The strangers had mounted the harpoon on the explorer's fore starboard landing strut and attached the launch pin to the console. Margot fumbled for the thick, metal pin and its trailing wire.

Well, just call me Ishmael, she thought, suppressing a giggle. There she is, Captain Ahab! There be the great white whale!

"Margot..." began Nick's stranger.

"Don't push," she snapped. Don't push. I might decide not to do this.

I could. I could not do this. I could leave the strangers out here. Never have to bring them home. Never have to hurt my friends families by showing them what's happened.

But I want to go home. Forgive me, Carol. Margot Rusch has to get home.

Margot grit her teeth. Ice crystals drifted past her. The comet retreated on its lumbering path, inanimate, or at least oblivious of their presence and their need.

Margot pulled the pin on the harpoon.

The recoil vibrated through the frame. The harpoon shot forward, hard, fast and straight. The tether vanished into the thick of the coma, lost in the shining veil of ice.

A jet of ice crystals exploded into the night. The comet rolled away as if wounded. The tethers on their reel played out into the void. Margot bit her lip. The tether was the key. If it released too fast, got tangled, or broke, it was over, all of it.

"Margot! Report!" demanded Nick's stranger.

"Tether holding steady," replied Margot reflexively. "Pay out looks good."

You'll get home. To Nick's home. That's what you care about.

The explorer shuddered. A sudden intense cold burned Margot's shin. A red warning light flashed on her visor screen.

No!

A black gash cut across her gleaming yellow suit. The joints at knee and ankle sealed off automatically. Margot fumbled for the roll of sealant tape on her belt. As she did, the explorer began to slide backward, away from the comet, toward the Forty-Niner to the limit of the tether. The movement dragged her back against her straps. Her glove gripped the tape reel. Pain bit deep.

Hang on, hang on. Lose the tape and you're gone. You're all gone. The stranger'll have you if you lose the tape.The tug grew stronger. Margot felt her body shoved backward to the limits of its straps. A weight pressed hard against her ribs, her throat, her heart. After years of zero g, the acceleration gripped her hard and squeezed until her breath came fast and shallow.

Ahead of her, the Forty-Niner began to swing. A slow, sinuous movement that transmitted itself along the tether. It pulled the explorer to starboard, tilting her personal world, confusing her further, adding to the pain that screamed through every nerve.

Slowly, slowly she pulled the roll of tape from her belt. She grasped it in both clumsy, gloved hands.

The explorer shimmied. Her body bounced up, then down, hard enough to jar her. The tape slipped.

Margot screamed involuntarily and clung to it so hard she felt the flimsy reel crumple.

"Margot?" Jean's stranger. "Margot? What's happening?"

"Don't unstrap!" came back Nick's stranger. "Jean, stay where you are."

Right, right. Why risk anything for me? I'm not a stranger.

She leaned forward as if leaning into a gale wind. Black spots danced in front of her vision. She saw red through the gash, as if her leg glowed with its pain. She jounced and shuddered. More hits. The explorer was taking more hits from cometary debris. She couldn't steady her hands enough to lay down the tape.

Margot bit her lip until she tasted blood. She pressed the tape reel against the black gash, pushed the release b.u.t.ton down and pulled, hard. A strip of clean white tape covered the black scoring.

The red light on her suit display turned green and the joints unsealed. Her suit was whole again.

Margot let herself fall backward, gasping for air, gasping for calm against the pain. Her left leg from ankle to knee would be one gigantic blood blister. But she was alive. The stranger hadn't got her yet. She hugged the tape to her chest. The Forty-Niner started swinging slowly back to port. Gravity leaned hard against her. Her heart labored, as if trying to pump sideways. Her stomach heaved. Her whole body strained against the straps.

She closed her eyes and tried to reach outward with every nerve, trying to feel the clamps and catches as she could her fingers and toes, wishing she could hear something, anything, a straining, a snapping. All there was was silence and the unbearable pressure driving her ribs into her lungs.

"Forty-Niner to Explorer One." Nick's stranger. What did he want? To find out if her stranger had swallowed her yet?

Not yet, Sir. Not yet.

"Margot? Margot, it looks like you're venting something. Report."

Venting? Margot's gaze jerked down to the monitor between her flight sticks. Red lights flashed. She didn't need to read the message. The diagram showed everything. The methane tank had been hit and all her fuel was streaming out into the void, leaving nothing at all for her to use to guide the explorer back to Forty-Niner.

She was stuck. She would hang out here until her air ran out. She was dead all over again.

All at once, the vibrations ceased. She was flying smooth and free, gliding like a bird on a sea wind with only the most gentle roll to perturb her flight.

"We have tether release!" cried Jean's stranger.

Margot looked up. A silver line lashed through the clean, sparkling white of the coma.

Tether release. They'd done it. It had worked. The strangers were all on their way home. She looked again at her own fountain of crystals streaming out behind her, a comet's tail in miniature.

That roll'll get worse. They'll have to correct for it. They'll have to fire the rockets and catch me in the blast and tell Jordan and mission control how sorry they were.

Nick's stranger spoke to her again. "Margot, we gotta get you in here. If your fuel's gone, can you haul on the tether? Margot?"

"She's not receiving, Nick. The headset must be out. I gotta get down there."

All gone. Nothing to do. Pain throbbed in her head, crowding out her thoughts.

"Margot, pull!"

She couldn't move. Pain, bright and sharp, burned through her. All she could do was watch the crystal stream of her fuel drift away into the vacuum.Margot Rusch is dead.

"Margot! Answer me! Pull, Margot!"

She's been dead for weeks.