He left the display and slumped back on his bunk. I went over and stared at it for a couple of minutes. “Would McAndrew know that this is here?”

That made him think instead of just brooding. “There’s a good chance that he would. Collapsed and high-density matter is Doctor Limperis’s special study, but McAndrew probably put a library of them into Merganser’s computer before he left. He wouldn’t want to run into something unexpected out here.”

“We have McAndrew’s probable trajectory stored there too?”

“We know how he left the System, where he was heading. If he cut the drive, or turned after he was outside tracking range, we don’t have any information on it.”

“Never mind that. Give me the library access codes, and let me get at the input console. I want to see if Mac’s path shows intersection with any of the high-density objects out here.”

Wenig looked skeptical. “The chances of such a close encounter are very small. One in millions or billions.”

I was already calling up the access sequence. “By accident? I’d agree with you. But McAndrew must have had some reason to fly back through the System, and make the slight course change that you recorded. I think he was telling us where he was going. And the only place he could have been going between here and Sirius would be one of the collapsed bodies out in the Halo.”

“But why?” Wenig was standing at my shoulder, fingers twitching.

“Don’t know that.” I stood up. “Here, you do it, you must have had plenty of experience with Dotterel’s computer. Set it for anything that would put Merganser within five million kilometers of a high-density body. That’s as close as I think we can rely on trajectory intersection.”

Wenig’s fingers were flying over the keys — he should have been a concert pianist. I’ve never seen anybody handle a programming sequence at that rate. While he was doing it the com-link whistled for attention. I turned to it, leaving Wenig calling out displays and index files.

“It’s Limperis,” I said. “Problems. President Velez is starting to breathe down his neck. Wants to know what has happened to Nina. When will she be back? Why did Limperis and the rest of you let her go on a test trip? How can the Institute be so irresponsible?”

“We expected that.” Wenig didn’t look up. “Velez is just blowing off steam. There’s no way that any other ship could get out here to us in less than three months. Does he have anything useful to suggest?”

“No. He’s threatening Limperis with punitive measures against the Institute. Says he’ll want a review of the whole organization.”

“Limperis is asking for our reply?”

“Yes.”

Wenig keyed in a final sequence of commands and sat back in his seat. “Tell him Velez should go fuck himself. We’ve got enough to do without interference.”

I was still reading the incoming signals from Triton Station. “I think Dr. Limperis has already sent that message to the President’s Office, in not quite those words. We’d better get Nina back safely.”

“I know that.” Wenig hit a couple of keys and an output stream began to fill the scope. “Here it comes. Closest approach distances for every body within five hundred AU, assuming McAndrew held the same course and acceleration all the way out. I’ve set it to stop if we get anything better than a million kilometers, and display everything that’s five million or closer.”

Before I could learn how to read the display, Wenig banged both hands down on the desk and leaned forward,

“Look at that!” His voice showed his surprise and excitement. “See it? That’s HC-183. It’s 322 AU from the Sun, and almost dead ahead of us. The computer shows a fly-by distance for Merganser too small to compute — that’s an underflow where we ought to see a distance.”

“Suppose that McAndrew decelerated as he got nearer to it?”

“Wouldn’t make much difference, he’d still be close to rendezvous — speeds in orbit are small that far out. But why would he want to rendezvous with HC-183?”

I couldn’t answer that, but maybe we were at least going to find Merganser. Even if it was only a vaporized trace on the surface of HC-183, where the ship hit it.

“Let’s get back with our drive,” I said. “What’s the mass of HC-183?”

“Pretty high.” Wenig frowned at the display. “We show a five thousand kilometer diameter and a mass that’s half of Jupiter’s. Must be a good lump of collapsed matter at the center of it. How close do you want to take us? And what acceleration for the drive?”

“Give us a trajectory that lets us take a close look from bound orbit. A million kilometers ought to be enough. And keep us down to twenty gee or better. I’ll send a message back to the Institute. If they have any more information on HC-183, we want it.”

Wenig had been impatient before, when we weren’t going anywhere in particular. Now that we had a target he couldn’t sit still. He was all over our three-meter living-capsule, fiddling with the scopes, the computer, and the control console. He kept looking wistfully at the drive setting, then at me.

I wasn’t having any. I felt as impatient as he did, but when we had come this far I didn’t want to find we’d duplicated all McAndrew’s actions, including the one that might have been fatal. We smoothly turned after twenty-two hours, so our drive began to decelerate us, and waited out the interminable delay as we crept closer to the dark mass of HC-183. We couldn’t see a sign of it on any of the sensors, but we knew it had to be there, hidden behind the plasma ball of the drive.

When our drive went off and we were in orbit around the black mass of the hidden proto-planet, Wenig was at the display console for visible wavelengths.

“I can see it,” he shouted.

My first feeling of relief and excitement lasted only a split second. There was no way we would be able to spot the Merganser from a million kilometers out.

“What are you seeing? Infrared emission from HC-183?”

“No, you noodle. I can see the ship — McAndrew’s ship.”

“You can’t be. We’d have to be right next to it to be able to pick it up with our magnifications.” I spun my seat around and looked at the screen.

Wenig was laughing, hysterical with relief. “Don’t you understand? I’m seeing the drive, not Merganser itself. Look at it, isn’t it beautiful?”

He was right. I felt as though I was losing my reason. McAndrew might have gone into orbit about the body, or if he were unlucky he might have run into it — but it made no sense that he’d be sitting here with the drive on. And from the look of the long tail of glowing plasma that stretched across twenty degrees of the screen, that drive was on a high setting.

“Give me a Doppler read-out,” I said. “Let’s find out what sort of orbit he’s in. Damn it, what’s he doing there, sight-seeing?”

Now that it looked as though we had found them, I was irrationally angry with McAndrew. He had brought us haring out beyond the limits of the System, and he was sitting there waiting when we arrived. Waiting, and that was all.

Wenig had called up a display and was sitting there staring at it in perplexity. “No motion relative to HC-183,” he said. “He’s not in an orbit around it, he’s got the ship just hanging there, with the drive balancing the gravitational attraction. Want me to take us alongside, so we can use a radar signal? That’s the only way he’ll hear us through the drive interference.”

“I guess we’ll have to. Take us up close to them.” I stared at the screen, random thoughts spinning around my head. “No, wait a minute. Damn it, once we set up the computer to take us in there, it will do automatic drive control. Before we go in, let’s find out what we’re in for. Can you estimate the strength of HC-183’s gravitational attraction at the distance that Merganser is at? Got enough data for it?”