She fell forward without a sound. Her attacker pulled a black square from inside his coat, opened it up to form a bag, and slid it around her. The metal bar went in next. Then he was lifting her-easy in the light gravity-and hurrying away with the bag in his arms. He did not enter a side passage, but traveled along the corridor until he was finally hidden from sight by its curve. The whole thing, from the appearance of Lucille DeNorville to the vanishing of her attacker, had occupied perhaps thirty seconds.

“Replay?” Seth asked, and reality came drifting back.

“Perhaps later. That’s it, the whole thing?”

“That’s it, squire. I agree, not much for three million bucks. Think we should ask for our money back?”

“How much of this was derived from established fact, and how much was conjecture?”

“We’re sure of a few things. How she was dressed, the fact that she died at that particular place. Like her, the weapon was never found. But that’s gotta be the way he killed her.”

“Got to be? Why?”

“Splashes of blood and scraps of brain tissue on the wall. The DNA tests confirm that they came from Lucille DeNorville. And they were splashes, not smears. No blood or body tissue anywhere else in that corridor, and I mean anywhere. The people DeNorville hired went over the corridor with every gadget ever made. The body must have gone into a bag or a box and been carted away.”

“Carried away by the murderer?”

“I guess so. Are you suggesting that there could have been two of ’em?”

“No. I merely wish to emphasize the boundary between knowledge and conjecture. Do you assume that she never saw or heard her murderer?”

Seth stared at me dubiously. He was, perhaps, wondering if his transatlantic journey was worthwhile. “Well, she couldn’t have, could she? The brain tissue came from the occipital lobe, they reckon from the left rear of her head. If she’d’ve heard him, she’d have turned and tried to defend herself.”

“That is plausible conjecture, but it is not fact. Suppose that she knew the murderer and was walking with him?” I was perhaps being deliberately perverse, since I could in truth see no reason to disagree with Seth’s conclusion.

He snorted. “What about the others, then? Did he know all of ’em?”

“That seems improbable.”

“Damn right it does. Even if he did know her, after six deaths wouldn’t you think that a young girl would get pretty damn careful who she’d walk with alone on Sky City?”

That thought had already occurred to me. I nodded, and Seth stared at me intently. “We’re up to number seven. Want to. hear about the other five, or do you need to take a break?”

He was observant. He looked as fresh as when we had started, but I doubt that was true of me. Even though I felt no kinship with the murderer, too many sea wraiths had been swirling up from the subterranean ocean of my past.

“Go ahead,” I said. “I am tired, but let us briefly review the other cases. Then I have to rest. I must inform you, however, that to this point I am utterly without ideas.”

It was rather worse than that. I could find no mental point of contact with the murderer, despite the fact that his victims interested me greatly.

Seth was not at all put out. “Fair enough,” he said. “I’ve worked this for weeks, an’ still got nowhere. I’ll go quick with number eight. Denise Braidley was twelve and a half years old. We think she was killed March twenty-second; at least that’s when she disappeared. But she’s another case where the body was never found, an’ it’s even possible it wasn’t a murder at all. Denise had a bit of a screw loose-three or four times in the past she’d grabbed a suit an’ took off into space by herself. Once she was gone for three days an’ rode way out past Cusp Station. Said when she got back she’d have liked to keep going all the way to Alpha Centauri. Fat chance. She couldn’t have gone farther than she did in the suit she had, an’ she was lucky one of the big scopes spotted her. If no one had seen her an’ stopped her, she’d not have made it home. She’d never bothered to make sure her suit was fully charged or the com unit was workin’. Maybe that’s what happened this time, she drifted off an’ died in open space.”

I shuddered, for reasons that Seth was unlikely to comprehend. He was continuing. “Number nine is more interesting. Julia Vansittart was killed April third, an’ her case is the closest anybody’s ever come to gettin’ a peek at the murderer. In fact, except for a bit of bad luck we’d have at least a low-definition picture of him. It’s pretty certain-l know what you’re thinkin’: facts, not conjectures-that Julia was murdered outside Sky City, an’ we know to within ten minutes when it happened.

“She an’ a bunch of other students had gone off in a science class to take a look at the power-generating equipment, out along the axis beyond the main structure. Routine hop in suits, some class does the same sort of thing every few weeks. There were ten kids in the bunch, an’ when they were done at the power-generation plant they were allowed to go back by themselves to a city entry port on level zero. Julia was in her suit when they left the power plant. All the others swear that. A quarter of an hour later, the rest of ’em were inside an’ ready to get out of their suits. One of her friends, Walt Christie, noticed that Julia wasn’t with ’em, so he popped back outside to see what was keepin’ her. He found her body floating in space, communication unit smashed and suit ruptured.

Somebody had skewered a line extender right through the suit, through her heart, an’ out the other side. Normally, the meteor detection systems would have caught a picture of what happened, but they were out of action for scheduled maintenance. A bit of luck for the killer.

“We have a reconstruction of what happened, but it come out lousy. I don’t think you should bother with it. You’ll get a much better idea when you see everythin’ for yourself.”

I had to concentrate hard to keep my self-control. My mind had filled with an image of the body of Julia Vansittart. It floated in the great void, lost in a cavernous emptiness without end.

You’ll get a much better idea when you see everythin’ for yourself.

Those words raised the level of my discomfort to the point where my record of the next five minutes is based on despised conjecture, rather than the hard evidence of accurate recall.

“What do you mean, see for myself?” I croaked, terrified by the implications of his statement.

“Up on Sky City.” Seth stared at me. “We gotta go there. Even the best reconstructions are nothin’ like the real thing. I was thinkin’, you get your head around the facts, then in a day or two the pair of us make a little trip.”

“No! Absolutely not.” The room was spinning around me. “A visit on my part to Sky City is totally impossible.”

“It is? Look, if you’re worried about gettin’ caught, you don’t have to. I got the system greased. I can make sure that nobody even suspects—”

“Did you not hear me?” I cried. “I cannot go to Sky City-or anywhere else in space.” And, when he stared at me, “Did you not check my background before you came here? Since childhood I have suffered from extreme forms of acrophobia and agoraphobia. I cannot, to save my life, tolerate heights or open spaces.” I pointed toward the invisible cliffs, half a mile to our west. “I can go no closer to the sea than we are now. As for outer space” — the very words caught in my throat — “in that intolerable environment I would be unable to think, to work, even to breathe.”

He did not, to his credit, argue or rage or deny the reality of the problem. Instead he stood up and went to stare into the dying fire. “I didn’t know that,” he said at last. “I should have. There’s nothin’ you can do about it? I mean, like with drugs and fizzes?”

“Nothing. I have tried. Anything that damps my reaction sufficiently to tolerate an open environment leaves me unable to think.”