I immediately adjust the third-stage engines on my interceptors, trying to deflect them away from the SS-27. But it's too late. There's not enough time to get away.

I'm less than a mile from the missile when Sigma springs its trap. The nuclear warhead explodes.

I'm floating in a sea of white light. Just like the last time I died.

The nuclear blast is so high up it doesn't scorch the ground. Instead, its radiation floods the emptiness of space and electrifies the upper atmosphere. The interceptor that's closer to the explosion gets the full brunt of the gamma rays, which pierce the steel skin of the rocket and penetrate its control unit. The radiation melts the neuromorphic circuits, fusing them together, destroying all the copies of my files in an instant. It feels like one of my stilts has just been knocked out from under me.

But I still have my files in the second interceptor, which is in a very lucky spot. The tip of the rocket, the part that contains the control unit and the radio, is directly behind the first interceptor. In a miracle of geometry, the first rocket blocks and absorbs the radiation that would've struck the second. In other words, my remaining control unit is in a gamma-ray shadow, the only piece of space for miles around that isn't fatally irradiated.

I'm relieved, but also bewildered. How did I get so ridiculously lucky? It can't be just chance. Something else must've happened. In the last milliseconds before the explosion I must've adjusted the path of the interceptors to set up this life-saving geometry. I don't remember doing it. But I must've.

Although the shadow protects my control unit, it doesn't cover the whole rocket. Gamma rays strike the bottom half of the interceptor and destroy the electronics that control the rocket engines. Without any electronics, the engines stop firing. And without any engines, my interceptor falls back into the grip of earth's gravity. The rocket coasts for a while, then starts to descend to the Russian countryside.

The descent is gentle at first. The interceptor slides back into the upper atmosphere, which is so thin it offers almost no resistance. After a couple of minutes, though, the downward slide grows steeper. I use the interceptor's radio to search for a neuromorphic control unit on the ground, maybe one of the extra units that General Hawke brought to Russia. But now I'm hundreds of miles northwest of Saratov, and all the signals from Hawke's control units are vanishingly faint. I've never tried to transfer my data that far. I don't even know if it's possible.

And yet Sigma did it. It sent its data to a satellite that was two hundred miles away. So I should be able to do it too. I turn on my data transmitter and establish a link with a control unit on top of a distant hill, just outside Tatishchevo Missile Base. Then I start sending my files.

The air resistance increases as I plunge into the lower atmosphere. According to my sensors, the friction is heating the steel skin of the interceptor. My radio antenna is embedded in that skin, and I know it'll melt if it gets much hotter. I'm shooting data as fast as I can toward the distant hilltop, but the interceptor is tumbling through the air now, making it difficult to maintain the radio link. My mind is stretched over a vast expanse of Russian farmland, and I'm falling fast. I'm not going to make it.

Sadness fills my circuits. More than anything, I want to see the Pioneers again. I make a final push, hurling my data out of the radio antenna and across the sky. Then the interceptor plummets through the clouds.

Good-bye, Shannon. Good-bye, DeShawn. Good- SHANNON'S LOG APRIL 8, 04:51 MOSCOW TIME.

"What's happening, General? Where are the interceptors?"

I'm using my T-90's radio to communicate with General Hawke, who's still on the hill where we left our Pioneers behind. The radio channel is full of static. Although the nuke exploded way up in space, a hundred miles above the ground, it generated a ton of electrical noise in the atmosphere.

"Give me a second, Gibbs. A lot of our equipment is busted. The pulse from the nuke knocked out all the electronics that weren't shielded."

"What about your radar? That's shielded, isn't it?"

"Hold on, I'm checking it now."

I can't stand it. Every second is torture. Losing Adam the first time was terrible enough. I don't know if I can survive losing him again.

Hawke's voice finally bursts through the static. "Okay, I see two tracks on the radar, both coming from the area where the missile exploded. The objects could be the interceptors, but it's hard to tell."

"Where are they?"

There's a pause before Hawke responds. It lasts only a couple of seconds, but it feels like an eternity. "Both objects just hit the ground. About two hundred miles northwest of here."

No. It's not true.

"Check the radar again."

"I'm sorry, Gibbs, but-"

"Check it again!"

There's another eternal pause. When Hawke comes back on the radio, his voice is softer and full of awe. "Holy smoke. I don't believe it."

"What? You saw something else on the radar?"

"No. It happened right here. One of the Pioneers just moved its arm."

CHAPTER.

24.

"Come on, Armstrong. Stop your dreaming."

It's true, I'm dreaming. But this time I'm not playing touch football in my backyard. This time I see Mom. She's young and happy and sitting on the edge of my bed. This is a memory from long ago, from the years before I got sick.

"Don't play games with me, Pioneer. The sensors say you're in there."

I don't want to leave her. I want to stay here forever. But the voice is insistent.

"You hear me? I'm giving you a direct order. Get your circuits in gear and pay attention."

I turn on the camera in my turret. General Hawke stands in front of me, dressed in combat fatigues. We're in a clearing on top of a wooded hill. It's almost dawn.

"I hear you." My synthesized voice is shaky. The robot I'm occupying feels familiar, but I know it can't be Pioneer 1 or 1A. "Where am I?"

"We're a couple of miles outside Tatishchevo Missile Base. This is where we launched the Ravens." Hawke points at the antenna rising from my turret. "After the nuke exploded, you transferred from the interceptor to Pioneer 2."

No wonder it feels familiar. I'm inside Jenny's Pioneer again. But now there's no trace of Jenny in the circuits. Not even the smallest thought.

A choking noise comes out of my speakers. I can't speak.

Hawke nods. "I'm sorry, Adam. The other Pioneers told me what happened to Jenny. They're still inside the missile base, riding in the T-90s, but I've been talking with them over the radio."

I turn my turret away from him. On the other side of the clearing are three immobile, unoccupied robots-Pioneers 4, 5, and 6. They're waiting for their rightful owners to return. I wonder for a moment why the radio signals from my interceptor connected with Jenny's Pioneer and not the others. Was it an accident? Or was I somehow drawn to her old circuits?

After a few seconds I can speak again. I turn back to Hawke. "Are the others okay?"

"Yeah, they're fine. Zia and Marshall used the lab's dish antenna to transfer to the T-90s. They joined up with Shannon and DeShawn, and then all four tanks turned their guns on the computer lab and obliterated the place. Sigma was long gone by then, but it never hurts to be thorough."

"What about Brittany? Did she get out in time?"

"We got a report about her from the Russian troops who are reoccupying the base. They said they found a young American girl running away from the headquarters. She's eating breakfast with the Russians now."

Thank God. No one else died. No one else was deleted. It could've been a whole lot worse. Sigma was planning to kill us all.

"Sigma escaped," I tell Hawke. "It transferred to the Globus-1 communications satellite. Can we shoot that thing down?"

The general shakes his head. "Sigma's virus infected all our anti-satellite weapons. And it's too late anyway. The AI already used the satellite's transponder to download itself to a ground station in China."

"So can we-"

"The ground station was connected to the Internet. Sigma jumped into the Internet's communication lines and disappeared. We can't track where it went."

"But it can't occupy an ordinary computer. The AI has to go someplace where there are neuromorphic circuits. That limits the number of possibilities, right?"

"Yeah, but not enough. It looks like Sigma had a backup plan. It found a hiding place it could use in case it got into trouble."

A surge of anxiety runs through me. I remember what Sigma said when I was in the interceptors, how this was just the first phase of the competition. Sooner or later we'll have to face the AI again.

Hawke steps closer, looking directly at my camera. He seems to sense my unease. "Don't worry, Armstrong. I got some good news for you, too. The rescue team in Colorado found your father. He's pretty banged up, but he's gonna be okay."

This piece of news is so amazing I have trouble believing it. "They found him? In the crashed helicopter?"

"You showed some good sense by getting him out of Pioneer Base and into the Black Hawk. The helicopter was full of medical supplies and cold-weather gear. Your dad was able to bandage his wounds and stay warm until the rescuers tracked down his emergency beacon."

Once again I can't speak, but now it's because I'm too happy. I don't feel anxious anymore, not one bit. Dad will be here to help us. He'll get us ready for whatever comes next.

"And you proved yourself again this morning," Hawke continues. "Judging from what the other Pioneers said, you and Zia distinguished yourselves in the fight against Sigma. So I'm willing to forgive your misconduct at Pioneer Base. You and Zia can stay in the Pioneer Corps on a probationary basis." He points his finger at my camera. "That means you better not screw up again. Understand?"

His eyes are stern, but he's also grinning. Although I'm still not sure if I like this man, he's become a familiar presence in my memory files, like a cranky uncle. I bend the elbow joint of my right arm and raise the steel hand in a salute. "Yes, sir."

A moment later my acoustic sensor picks up a loud rumbling behind me. I turn my turret around just in time to see a T-90 battle tank come up the trail to the hilltop. Three more T-90s follow right behind. The four tanks halt in the middle of the clearing, lined up side by side. Then the Pioneers transmit their data back to the robots.

Shannon is the first to complete the transfer. Pioneer 4 bounds toward me, her robotic arms stretched wide. She nearly knocks me over as she hugs me. Our armored torsos clang together, and the noise echoes across the clearing.

Then DeShawn crashes into us, slapping his hands against our turrets. Marshall strides toward us a moment later and DeShawn hugs him too. Zia stays in her T-90 because she has no Pioneer to transfer to, but she joins in the celebration by pointing her anti-aircraft gun at the sky and firing tracer rounds into the brightening dawn. They look like fireworks.

After a while we step backward and stand in a huddle, facing each other. DeShawn clenches his steel hands into fists and starts beating them against his torso. At the same time, he lets out a howl, a deep wordless yell that booms out of his speakers. It's a cry of joy and sadness and triumph. Soon we're all doing it, howling and beating our fists against our armor. The noise is deafening. The Russian and American soldiers retreat to the edge of the clearing, covering their ears. Zia's tracer rounds arc toward the rising sun.

We're celebrating our victory. And mourning Jenny. It was a painful, horrible battle, but we won. We won. After a few seconds I realize I'm not howling anymore. The sound coming out of my speakers is purely joyous now.

I'm laughing. I can laugh again. I finally figured it out.

EPILOGUE.

Two Months Later.

We couldn't go back to Pioneer Base, of course. Instead, General Hawke sent us to White Sands Missile Range, the huge Army base in New Mexico. Hawke says the Army is going to build a new home for the Pioneers, but until then we're living in a compound at the edge of the desert, with barren mountains to the west of us and a sea of sand dunes to the east. It's a restricted area, which means the only people here are heavily armed soldiers.

Our compound has just two buildings: a barracks and a storage depot. Behind them is a wide plain of hard-packed dirt that I've turned into a football field, making gouges in the ground to mark the end zones and sidelines. Because the field is meant for Pioneers, not people, it's about three times bigger than a regulation NFL field. All five of us have played there a few times, but Marshall isn't so crazy about football and Zia gets way too competitive. So mostly it's just Shannon and DeShawn and me who come here. We use an official Super Bowl XLVI football, a new one that Dad bought for me on eBay to replace the one I lost at Pioneer Base.

The three of us are on the field on a blindingly hot afternoon, tossing the football around, when I see a car coming up the dirt road from the south. It's almost three miles away, but when I zoom in on it with my camera, I see that it's Dad's car. He left the compound this morning to go to the White Sands headquarters, near the town of Las Cruces. He was a little mysterious when I asked him why he was going there. All he would say was that he might bring back a surprise for me. Now I focus on the car's windshield and magnify the image as much as I can. Someone's sitting in the passenger seat. I can't make out who it is from this distance, but I notice that the figure has long hair. Definitely female.

It must be Brittany. Ever since the battle at Tatishchevo, she's been trying to visit me. At first General Hawke hated the idea; in his opinion, Brittany was an unstable girl who already knew too much about the Pioneer Project. So we returned to the United States in different planes, the Pioneers in the cargo hold of our C-17 and Brittany in a private jet with Hawke and his deputies.

During the flight, though, the general convinced Brittany to enter a counseling program for troubled teens when she got back to New York. The counselors found a youth shelter for her in Manhattan and even a special high school where she could get her diploma. Hawke told me yesterday he's changed his mind about Brittany and might allow her to visit our compound. But now I'm starting to wonder whether it's a good idea. I'm still worried about how she'll react when she sees me.

Shannon and DeShawn focus their cameras on the car. I'm sure they also see the female passenger. Without a word, they stride back to the barracks.

Now I'm alone and nervous, and the car is still two miles away. I wish Dad had talked to me before springing this surprise. It would've been better to wait. The Army is building new robots for us, and DeShawn-who's helping to design the machines-says they'll be more humanlike than the ones we have now. But the new robots might be just as frightening anyway, because they'll be equipped with more weapons. Although there's been no sign of Sigma for the past two months, everyone's preparing for the next battle with the AI. General Hawke is especially concerned about the anthrax. After the Russian soldiers captured Imran Daudov, he led them to a warehouse at Tatishchevo where he and the other terrorists had hidden the deadly germs. But the anthrax wasn't there. It had vanished along with Sigma.

When the car is a mile away I dart behind the storage depot. Leaning my torso to the side, I peek around the corner of the building as Dad drives down the dusty road. Soon he slows the car and parks in front of the barracks. He gets out and walks around the car, limping from the two-month-old injuries to his legs. Then he opens the passenger-side door.

The passenger steps out. It's not Brittany. It's my mother.

She's changed so much. Her hair is totally gray now. She's thinner too, and her black dress hangs loosely from her shoulders. But her face is the same-sad, tired, fragile, loving. The image is engraved in my circuits.

I start running toward her. I can't help it. I leap from behind the storage depot and stomp through the dirt in front of the barracks. "Mom! Mom!"

This is a mistake. Mom clutches Dad's polo shirt and cowers beside him. I stop in my tracks, about twenty feet away, but the damage is done. If Mom wasn't holding on to Dad, she'd collapse in a heap.

I step backward, lifting my steel hands in the air. "Oh God, I'm so sorry! I didn't mean to scare you!"

Dad takes a deep breath. "Adam, lower your volume." Then he puts his arm around Mom's shoulders. "It's okay, Anne. We're perfectly safe."

She doesn't say anything. She just shakes her head.

Dad squeezes her shoulder. "He saved my life, remember?"

Despite the hundred-degree heat, Mom's shivering. The fabric of Dad's shirt is bunched between her fingers. I want to comfort her, but I'm afraid to say anything now. I might start crying, and that would probably freak her out even more.

After several seconds she lets go of Dad and whispers something in his ear. Then she bites her lip and looks at me. "I came here to say thank you." Her voice is so low my acoustic sensor can barely pick it up. "Thank you for saving my husband."

"Mom, I-"

"Please don't call me that. I had a son, but he died."

I knew she was going to say this, but it's still a blow. I feel hollow, numb. Like a soulless machine.

"I'm not your mother," she continues. "But I want to be your friend. Tom has told me all about you, everything that happened in Colorado and Russia. You have all the bravery and kindness that my son had. And Adam was so wonderful. He was so-"

She buries her face in Dad's shirt. I take a step toward them, but Dad gives me a warning look, so I stop. He pats Mom's back as she cries.