I couldn’t decide if I was being complimented or not. As L-4 Station crept into view on the forward screen, I peered at it on highest magnification, trying to see what the rescue ship looked like. I could see the bulk of the Institute structure but no sign of anything that ought to be a ship. I had visions of a sort of super-Assembly, a huge cluster of electromagnetically linked spheres. All I could see were living quarters and docking facilities, and, as we came in to dock, a peculiar construction like a flat, shiny plate with a long thin spike protruding from the center. It looked nothing like any USF ship, passenger or cargo.

Limperis may have spent his whole life in pure research, but he knew how to organize for emergency action. There were just five people in our meeting inside the Institute. I had never met them in person, but they were all familiar to me through McAndrew’s descriptions, and from media coverage. Limperis himself had made a life study of high-density matter. He knew every kernel below lunar mass out to a couple of hundred astronomical units — many of them he had visited, and a few of the small ones he had shunted back with him to the Inner System, to use as power supplies.

Siclaro was the specialist in kernel energy extraction. The Kerr-Newman black holes were well-understood theoretically, but efficient use of them was still a matter for experts. When the USF wanted to know the best way to draw off power, for drives or for general use, Siclaro was usually called in. His name on a recommendation was like a stamp of approval that few would think to question.

With Gowers there as an expert in multiple kernel arrays, Macedo as the System authority in electromagnetic coupling, and Wenig the master of compressed matter stability, the combined intellect in that one room in the Institute was overpowering. I looked at the three men and two women who had just been introduced to me, and felt like a gorilla in a ballet. I might make the right movements, but I wouldn’t know what was going on.

“Look, Dr. Limperis,” I said, “I know what Professor McAndrew wants, but I’m not sure he’s right.” Might as well hit them with my worries at the beginning, and not waste everybody’s time. “I can run a ship, sure — it’s not hard. But I’ve no idea how to run something with a McAndrew drive on it. Any one of you could probably do a better job.”

Limperis was looking apologetic again. “Yes and no, Captain Roker. We could all handle the ship, any one of us. The concepts behind it are simple — a hundred and fifty years old. And the engineering has been kept simple, too, since we are dealing with a prototype.”

“Then what do you want me for?” I won’t say I was angry, but I was uneasy and unhappy, and there’s a fine line between irritation and discomfort.

“Dr. Wenig will drive the Dotterel, he has handled it before in an earlier test. Actually, he handled the Merganser, the ship that Dr. McAndrew has disappeared in, but the Dotterel has identical design and equipment. Controlling the ship is easy — if everything behaves as we expected. If something goes wrong — and something must have gone wrong, or McAndrew would be back before this — then neither Dr. Wenig, nor any of the rest of us, has the experience that will be needed. We want you to tell Dr. Wenig what not to do. You’ve been through dangerous times before.” He looked pleading. “Will you observe our actions, and use your experience to advise us?”

Uninvited, I flopped down into a seat and stared at the five of them. “You want me to be a bloody canary!”

“A canary?” Wenig was small and slight, with a luxuriant black mustache. He had a strong accent, and I think he was suspecting himself of a translation error.

“Right. Back when people used to go down deep in the earth to mine coal, they used to take a canary along with them. It was more sensitive to poisonous gases than they were. When it fell off the perch, they knew it was time to leave. The rest of you will fly the ship, and watch for me to fall off my seat.”

They looked at each other, and finally Limperis nodded. “We need a canary, Captain Roker. None of us here knows how to sing at the right time. Will you do it?”

I had no choice. Not after Mac’s personal cry for help. I could see one problem — I’d be telling them everything they did was dangerous. When you have a new piece of technology, it is risky, whatever you do with it.

“You mean you’ll let me overrule all the rest of you, if I don’t feel comfortable?”

“We would.” Limperis was quite firm about it. “But the question will not arise. The Merganser and the Dotterel are both two-person ships. We saw no point in making them larger. Dr. Wenig will fly the Dotterel, and you will be the only other person aboard. It just takes one person to handle the controls. You will be there to advise of hidden problems.”

I stood up. “Let’s go. I don’t think I can see danger any better than you can, but I may be wrong. If Mac’s on his own out there, wherever he is, we’d better get moving. I’m ready when you are, Dr. Wenig.”

Nobody moved. Maybe McAndrew and Limperis were right about my antennae, because at that moment I had a premonition of new problems. I looked around at the uncomfortable faces.

“Professor McAndrew isn’t actually alone on the Merganser.” It was Emma Gowers who spoke first. “He has a passenger with him on the ship.”

“Someone from the Institute?”

She shook her head. “Nina Velez is with him.”

“Nina Velez? You don’t mean President Velez’s daughter — the one with AG News?”

She nodded. “The same.”

I sat down again in my chair. Hard. Maybe the Body-beautiful run to Titan had been an easier trip than I had realized.

Wenig may have come to piloting second-hand, but he certainly knew his ship. He wanted me to know it, too. Before we left the Institute, we’d done the lot — schematics, models, components, power, life support, mechanicals, electricals, electronics, controls, and backups.

When the ship was explained to me, I decided that McAndrew didn’t really see round corners when he thought. It was just that things were obvious to him before they were explained, and obvious to other people afterwards. I had been saying “inertia-less” to Mac, and he had been just as often saying “impossible.” But we hadn’t been communicating very well. All I wanted was a drive that would let us accelerate at multiple gees without flattening the passengers. To McAndrew, that was a simple requirement, one that he could easily satisfy — but there was no question of doing away with inertia, of passengers or ship.

“Take it back to basics,” said Wenig, when he was showing me how the Dotterel worked. “Remember the equivalence principle? That’s at the heart of it. There is no way of distinguishing an accelerated motion from a gravitational field force, right?”

I had no trouble with that. It was freshman physics. “Sure. You’d be flattened just as well in a really high gravity field as you would in a ship accelerating at fifty gee. But where does it get you?”

“Imagine that you were standing on something with a hefty gravity field — Jupiter, say. You’d experience a downward force of about two and a half gee. Now suppose that somebody could accelerate Jupiter away from you, downwards, at two and a half gee. You’d fall towards it, but you’d never reach it — it would be accelerating at the same rate as you are. And you’d feel as though you were in free fall, but so far as the rest of the Universe is concerned you’d be accelerating at two and a half gee, same as Jupiter. That’s what the equivalence principle is telling us, that acceleration and gravity can cancel out, if they’re set up to be equal and opposite.”