The snake had wriggled its way free of the sheet. I saw its head lift again, turning and questing. Seth pointed what he was holding toward the snake. There was a flash of green light, and the head and long neck vanished. The room filled with smoke. Seth took a step forward, reached down, and whipped the sheet clear. Again I could see nothing. With the head gone, the rest of the intruder was too low to the ground to be in my field of view.
“I think that’s the main job done,” Seth said calmly. “But just in case, I think we’d be better off without them legs.” He pointed the gun downward and I saw eight separate flashes of green light.
“And now let’s have a look at you.” He reached down, picked something up, and deposited it on the bed.
It was perhaps a meter long. I saw blunt stumps, four on each side, where the legs had been, and the remaining stub of the severed snake neck.
“A cleaning machine,” I said.
“Nah.” Seth shook his head. He glanced across to where the RV jacket hung on the wall. “Nice work, Doc. I coulda been dead meat without the warnin’.”
“Could have been?”
“I was only half asleep. I mighta been all right.”
“You think perhaps that it did not intend you harm?”
“You kiddin’? Take a look.” He walked a couple of paces and picked something from the floor. He held it toward the RV jacket for my inspection. “Construction laser, lot more powerful than the one I got. Good thing I fired first, or I’d’ve been Parsigian Cajun-style, charred on the outside and well done on the inside.”
I am not unacquainted with death, but blood, carnage, and general messiness have never been a part of my own modus operandi. Everything here had happened so fast that I was only now beginning to react, with a fluttering pulse and a certain difficulty in breathing. I stared at the gun and at the mutilated object on the bed.
“If that is not a cleaning machine . . .”
I ran out of breath before I could complete my question, but Seth took my meaning. He went to the side of the bed, lifted the object by the stubby neck, and turned it over for my inspection.
“See this?” He pointed to a series of marks on the underside. “Series and model number, too high-level for a cleaning machine. It’s a general-purpose rolfe. If you look here on the side, you’ll see the place where it can plug in for instruction transfers. Hm. I guess this one’s too high-powered for me, too, ’cause I never saw this model number before. Must be one of the new ones, fresh up from Earth.”
“You are sure that it was programmed to attack you?”
Seth was still bending over the rolfe. He raised his head. “Not attack. Kill. That laser wasn’t brought along to give me a nice all-over tan. You oughta be sure of that, if anyone is. You were the one, way back when, who asked if a cleanin’ machine could be made to kill. You were the one, just tonight, who told me to watch out for my ass an’ hat ’cause I might be in danger. Why were you watchin’ me, anyway?”
“I was worried that the Sky City murderer might learn what we are doing and try to kill you to prevent it. The idea of sending a rolfe for that purpose never occurred to me.”
“Me neither. An’ I don’t think that’s what’s goin’ on.” Seth sat down on his bed next to the machine. “This ain’t from our buddy the killer. This is somethin’ else.”
“If not the murderer, then who?”
“I’m not sure. But I got ideas. An’ don’t worry, I’ll find out.” He nodded toward the remains of the machine. “Stumpy Joe there is blind an’ can’t go a-walkin’ no more, but the brain oughta be intact. I’m gonna bring that thing to engineering, bust it open, an’ squeeze the sucker dry. Then we’ll find out where it got its instruction set.”
“And after that?”
“Depends what I find. But don’t be surprised if you catch me havin’ a few words with Maddy Wheat-stone.” He stood up. “D’you see much action here in the next few days?”
“We cannot proceed with my plan until Sky City and Cusp Station are in their final locations. For what we have in mind, our timing and the killer’s psychological condition will both be crucial. I would prefer to act at the height of the particle storm. Why do you ask?”
“Just thinkin’ ahead.” Seth picked up the battered rolfe. “If I get the answers I’m suspectin’ out of this thing, I might have to make a little trip. But don’t worry, I’ll be back in plenty of time for your fun an’ games.”
He walked out, leaving me to stare at the empty room. I removed the RV helmet, took it back to my study, and stared at the wall clock in disbelief. Everything, from that first flicker of movement at Seth’s door to this moment, had occupied almost no time at all. Five minutes ago I had drifted between fairy stories and the strange no-man’s-land of impending sleep. Now I was totally wired, nerves jangling at the close escape from death.
I told myself this was Seth’s escape, not mine. I was not, and never had been, in the slightest danger. And Seth felt certain that the Sky City killer was in no way involved.
Curiously, I found I believed him. The murderer had done nothing, because the murderer needed to do nothing. We had no evidence. The killer’s safest course of action was continued total inaction.
Why, then, do I believe that Seth and I have a chance of success? Because human beings find it difficult to act on facts alone. We are plagued by overactive imaginations. And of the things that human beings are called upon to do, doing nothing can be the most difficult act of all.
27
John Hyslop scanned the table of values. If an anomaly was present, he couldn’t see it. “Are you sure?”
Amanda Corrigan nodded. Shy in a group, she was perfectly self-confident one-on-one. “It’s there. Hard to tell from the table of numbers, but when it’s graphed it jumps right out at you. See for yourself.”
She flashed up a different display, this one a curve of particle number against time. It showed a lopsided Gaussian distribution, the smooth mountain of the bell curve rising rapidly and then falling back to zero. On the left side of the mountain a secondary peak jutted up as a steep little hill.
John studied it. “Not much to look at.”
“It’s not, in terms of the maximum particle flux. Less than one percent.”
“But more than enough to cause trouble. Where did this curve come from?”
“Data from the Sniffer that we launched two weeks ago.”
“As a crash priority. What are the chances that something on board isn’t working right?”
“Poor. The Sniffer passed every test we threw at it.”
“Then we’d better start worrying about the earlier Sniffers. They were designed to catch this sort of thing, and they missed it.”
“Not really.” Amanda did more fast work at the pad.
“Here’s what the other Sniffers gave us, the way it was presented for visual analysis.”
John rubbed his eyes. The new curve he was looking at showed a single mountain with no bordering foothills. Maybe he was getting old. He had drunk wine with dinner, but that wasn’t it. After midnight he couldn’t keep up with Amanda’s speed and adolescent energy. She might be twenty-six, but she was like a fourteen-year-old in more than outward appearance.
“No peaks that I can see.”
“Right. No peaks.”
“Amanda, a peak in particle numbers can’t pop up from nowhere. It represents a physical entity.”
“It didn’t come from nowhere. The Sniffers are working correctly — all of them. What you are seeing is a combination of the physical limitations of the earlier instruments and the way we handle their data. I’ll show you.”
More dancing fingerwork from Amanda, and another display flashed into view.
“These are raw counts from one of the old Sniffers. The older models measure only what they find right in front of them, and they make readings every two seconds. That sounds like frequent sampling, but the relative speed of the particles and the Sniffers means we have only one sample every fifty thousand kilometers. I think of the data as a count of the number of particles at each cross section of a long, thin tube stretching from Earth toward Alpha Centauri. The particles come in bunches and clusters, so the counts have high statistical variation. Lots of hash in the data, hard to analyze. The peak I just showed you is present in the counts, but it’s really hard to see because of the noise in the signal. Now I apply a low-pass filter to the input, and there’s the resulting profile. Nice and smooth, but no peak. We see the major increases and decreases. The minor blip disappears.”