Holy shit," said Amos in a flat voice.

"Jim," Naomi said to Holden's back, but he waved her off and opened a channel to Alex in the cockpit.

"Alex, did we just see what my sensors say we saw?"

"Yeah, Cap," the pilot replied. "Radar and scopes are both sayin' Eros jumped two hundred klicks spinward in a little less than a minute."

"Holy shit," Amos repeated in exactly the same emotionless tone. The metallic bang of deck hatches opening and closing echoed through the ship, signaling Amos' approach up the crew ladder.

Holden shook off the flush of irritation he felt at Amos' leaving his post. He'd deal with that later. He needed to be sure that the Rocinante and her crew hadn't just experienced a group hallucination.

"Naomi, give me comms," he said.

Naomi turned around in her chair to face him, her face ashen.

"How can you be so calm?" she asked.

"Panic won't help. We need to know what's going on before we can plan intelligently. Please transfer the comms to me."

"Holy shit," Amos said as he climbed into the ops deck. The deck hatch shut with a punctuating bang.

"I don't remember ordering you to leave your post, sailor," Holden said.

"Plan intelligently," Naomi said like they were words in a foreign language that she almost understood. "Plan intelligently."

Amos threw himself at a chair hard enough that the cushioning gel grabbed him and kept him from bouncing off.

"Eros is really fucking big," Amos said.

"Plan intelligently," Naomi repeated, speaking to herself now.

"I mean, really fucking big," Amos said. "Do you know how much energy it took to spin that rock up? I mean, it took years to do that shit."

Holden put his headset on to drown Amos and Naomi out, and called up Alex again.

"Alex, is Eros still changing velocity?"

"No, Cap. Just sitting there like a rock."

"Okay," Holden said. "Amos and Naomi are vapor locked. How are you doing?"

"Not taking my hands off the stick while that bastard is anywhere in my space, that's for damn sure."

Thank God for military training, Holden thought.

"Good, keep us at a constant distance of five thousand klicks until I say otherwise. Let me know if it moves again, even an inch."

"Roger that, Cap," said Alex.

Holden took off his headset and turned to face the rest of the crew. Amos was looking at the ceiling, ticking points off with his fingers, his eyes unfocused.

" - don't really remember the mass of Eros off the top of my head... " he was saying to no one in particular.

"About seven thousand trillion kilos," Naomi replied. "Give or take. And the heat signature's up about two degrees."

"Jesus," the mechanic said. "I can't do that math in my head. That much mass coming up two degrees like that?"

"A lot," Holden said. "So let's move on - "

"About ten exajoules," Naomi said. "That's just off the top of my head, but I'm not off by an order of magnitude or anything."

Amos whistled.

"Ten exajoules is like, what, a two-gigaton fusion bomb?"

"It's about a hundred kilos converted directly to energy," Naomi said. Her voice began to steady. "Which, of course, we couldn't do. But at least whatever they did wasn't magic."

Holden's mind grabbed on to her words with an almost physical sensation. Naomi was, in fact, about the smartest person he knew. She had just spoken directly to the half-articulated fear he'd been harboring since Eros had jumped sideways: that this was magic, that the protomolecule didn't have to obey the laws of physics. Because if that was true, humans didn't stand a chance.

"Explain," he said.

"Well," she replied, tapping on her keypad. "Heating Eros up didn't move it. So I assume that means it was waste heat from whatever it was they actually did."

"And that means?"

"That entropy still exists. That they can't convert mass to energy with perfect efficiency. That their machines or processes or whatever they use to move seven thousand trillion tons of rock wastes some energy. About a two-gigaton bomb's worth of it."

"Ah."

"You couldn't move Eros two hundred kilometers with a two-gigaton bomb," Amos said with a snort.

"No, you couldn't," Naomi replied. "This is just the leftovers. Heat by-product. Their efficiency is still off the charts, but it isn't perfect. Which means the laws of physics still hold. Which means it isn't magic."

"Might as well be," Amos said.

Naomi looked at Holden.

"So, we - " he started when Alex interrupted over the shipwide comm.

"Cap, Eros is movin' again."

"Follow it, get me a course and speed as soon as you can," Holden said, turning back to his console. "Amos, get back down to engineering. If you leave it again without a direct order, I'll have the XO beat you to death with a pipe wrench."

The only reply was the hiss of the deck hatch opening and the bang as it closed behind the descending mechanic.

"Alex," Holden said, staring at the data stream the Rocinante was feeding him about Eros. "Tell me something."

"Sunward is all we know for sure," Alex replied, his voice still calm and professional. When Holden had been in the military, he'd been officer track right from the start. He'd never been to military pilot school, but he knew that years of training had compartmentalized Alex's brain into two halves: piloting problems and, secondarily, everything else. Matching Eros and getting a course for it was the former. Extra-solar space aliens trying to destroy humanity wasn't a piloting issue and could be safely ignored until he left the cockpit. He might have a nervous breakdown afterward, but until then, Alex would keep doing his job.

"Drop back to fifty thousand klicks and maintain a constant distance," Holden told him.

"Huh," said Alex. "Maintainin' a constant distance might be tough, Cap. Eros just disappeared off the radar."

Holden felt his throat go tight.

"Say again?"

"Eros just disappeared off the radar," Alex was saying, but Holden was already punching up the sensor suite to check for himself. His telescopes showed the rock still moving on its new course toward the sun. Thermal imaging showed it as slightly warmer than space. The weird feed of voices and madness that had been leaking out of the station was still detectable, if faint. But radar said there was nothing there.

Magic, a small voice at the back of his mind said again.

No, not magic. Humans had stealth ships too. It was just a matter of absorbing the radar's energy rather than reflecting it. But suddenly, keeping the asteroid in visual range became all the more important. Eros had shown that it could move fast and maneuver wildly, and it was now invisible to radar. It was entirely possible that a mountain-sized rock could disappear completely.

Gravity began to pile up as the Roci chased Eros toward the sun.

"Naomi?"

She looked up at him. The fear was still in her eyes, but she was holding it together. For now.

"Jim?"

"The comm? Could you...?"

The chagrin on her face was the most reassuring thing he'd seen in hours. She shifted control to his station, and he opened a connection request.

"UNN corvette, this is the Rocinante, please respond."

"Go ahead, Rocinante," the other ship said after half a minute of static.

"Calling to confirm our sensor data," Holden said, then transmitted the data regarding Eros' movement. "You guys seeing the same thing?"

Another delay, this one longer.

"Roger that, Rocinante."

"I know we were just about to shoot each other and all, but I think we're a little past that now," Holden said. "Anyway, we're chasing the rock. If we lose sight of it, we might never find it again. Want to come with? Might be nice to have some backup if it decides to shoot at us or something."

Another delay, this one almost two minutes long; then a different voice came on the line. Older, female, and totally lacking the arrogance and anger of the young male voice he'd been dealing with so far.

"Rocinante, this is Captain McBride of the UNN Escort Vessel Ravi." Ah, thought Holden. I've been talking to the first officer all along. The captain finally took the horn. That might be a good sign. "I've sent word to fleet command, but it's a twenty-three minute lag right now, and that rock's putting on speed. You have a plan?"

"Not really, Ravi. Just follow and gather intel until we find an opportunity to do something that makes a difference. But if you came along, maybe none of your people will shoot at us accidentally while we figure it out."

There was a long pause. Holden knew that the captain of the Ravi was weighing the chance that he was telling the truth against the threat he'd made against their science vessel. What if he was in on whatever was happening? He'd be wondering the same thing in their position.

"Look," he said. "I've told you my name. James Holden. I served as a lieutenant in the UNN. My records should be on file. It'll show a dishonorable discharge, but they'll also show that my family lives in Montana. I don't want that rock to hit Earth any more than you do."

The silence on the other end continued for another few minutes.

"Captain," she said, "I believe my superiors would want me to keep an eye on you. We'll be coming along for the ride while the brains figure this out."

Holden let out a long, noisy exhale.

"Thanks for that, McBride. Keep trying to get your people on the line. I'm going to make a few calls myself. Two corvettes are not going to fix this problem."

"Roger that," the Ravi replied, then killed the connection.

"I've opened a connection with Tycho," Naomi said.

Holden leaned back in his chair, the mounting gravity of their acceleration pressing against him. A watery lump was gathering low in his gut, the loose knot telling him that he had no idea what he was doing, that all the best plans had failed, and that the end was near. The brief hope he'd felt was already starting to slip away.

How can you be so calm?

I think I'm watching the end of the human race, Holden thought. I'm calling Fred so that it isn't my fault when no one has an idea how to stop it. Of course I'm not calm.

I'm just spreading the guilt.

"How fast?" Fred Johnson asked incredulously.

"Four g's now and climbing," Holden replied, his voice thick as his throat compressed. "Oh, and it's invisible to radar now."

"Four g. Do you know how heavy Eros is?"

"There's, uh, been some discussion," Holden said, only the acceleration keeping his impatience from showing in his voice. "The question is, now what? The Nauvoo missed. Our plans are shot to shit."

There was another perceptible increase in pressure as Alex sped the ship up to keep up with Eros. A little while longer and speech wouldn't be possible.

"It's definitely headed for Earth?" Fred asked.

"Alex and Naomi are ninety percent or so. Hard to be totally accurate when we can only use visual data. But I trust them. I'd go to where there are thirty billion new hosts too."

Thirty billion new hosts. Eight of whom were his parents. He imagined Father Tom as a bundle of tubes oozing brown goo. Mother Elise as a rib cage dragging itself across the floor with one skeletal arm. And with that much biomass, what could it do then? Move Earth? Turn out the sun?

"Have to warn them," Holden said, trying not to strangle on his own tongue as he spoke.

"You don't think they know?"

"They see a threat. They may not see the end of all native life in the solar system," Holden said. "You wanted a reason to sit at the table? How about this one: Come together or die."

Fred was quiet for a moment. Background radiation spoke to Holden in mystic whispers full of dire portents while he waited. Newcomer, it said. Hang around for fourteen billion years or so. See what I've seen. Then all this nonsense won't seem so important.

"I'll see what I can do," Fred said, interrupting the universe's lecture on transience. "In the meantime, what are you going to do?"

Get outrun by a rock and then watch the cradle of humanity die.

"I'm open to suggestions," Holden said.

"Maybe you could detonate some of the surface nukes the demo team put down. Deflect Eros' course. Buy us time."

"They're on proximity fuses. Can't set them off," Holden said, the last word turning into a yelp as his chair stabbed him in a dozen different places and injected him full of fire. Alex had hit them with the juice, which meant Eros was still speeding up, and he was worried they'd all black out. How fast was it going to go? Even on the juice they couldn't sustain prolonged acceleration past seven or eight g without serious risk. If Eros kept this rate of increase up, it would outrun them.

"You can remote detonate," Fred said. "Miller will have the codes. Have the demo team calculate which ones to set off for maximum effect."

"Roger that," Holden said. "I'll give Miller a call."

"I'll work on the inners," Fred said, using the Belter slang without a hint of self-consciousness. "See what I can do."

Holden broke the connection, then linked up to Miller's ship.

"Yo," said whoever was manning the radio there.

"This is Holden, on the Rocinante. Give me Miller."

"Uh... " said the voice. "Okay."

There was a click, then static, then Miller saying hello with a faint echo. Still wearing his helmet, then.

"Miller, this is Holden. We need to talk about what just happened."

"Eros moved."

Miller sounded strange, his voice distant, as though he was only barely paying attention to the conversation. Holden felt a flush of irritation but tamped it back down. He needed Miller right now, whether he wanted to or not.

"Look," he said. "I've talked to Fred and he wants us to coordinate with your demo guys. You've got remote codes. If we set off all of them on one side, we can deflect its course. Get your techs on the line, and we'll work it out."

"Huh, yeah, that sounds like a good idea. I'll send the codes along," said Miller, his voice no longer distant, but holding back a laugh. Like a man about to tell the punch line of a really good joke. "But I can't really help you with the techs."

"Shit, Miller, you pissed those people off, too?"

Miller did laugh now, a free, soft sound that someone who wasn't piling on g could afford. If there was a punch line, Holden had missed it.

"Yeah," Miller said. "Probably. But that's not why I can't get them for you. I'm not on the ship with them."

"What?"

"I'm still on Eros."