Derec went to the console and extended his hand. "Derec Avery."

"Tathis Kedder."

"I have floor work to do," Jeffries announced. "You need me, find me."

With that, she pivoted on her toes and left the room.

Derec waited several seconds. People returned to what they had been doing. "All right, what happened?" he asked Kedder quietly.

"Well…" Kedder gazed down at the console as if trying to remember what to do with it.

The other man at the board started tapping keys deftly. The row of screens at the top of the console cleared to milky white, then new images winked into place.

Kedder cleared his throat and pointed. "These are the, uh, primary monitor views leading up to the arrival of Senator Eliton."

"What the RI saw?" Derec asked.

"Uh-huh."

Robots moved quickly among the prep people who established the boundaries for spectators and ushered the public into their assigned areas. Quickly, the space filled. Then the first wave of dignitaries arrived. Derec checked the elapsed time: the sequence moved at roughly twice normal speed. The platform became crowded, security robots followed humans around, guaranteeing free access from the main entrance to the platform, accompanying more dignitaries in, herding the throngs of people. Eliton's entourage came in, and Derec's throat tightened at the sight of Bogard. So it had been here.

But what went wrong? he wondered.

"Now," Kedder said, "let's slow it back down to normal speed. Watch the audience."

The swift efficiency of the free-floating staff and security abruptly shifted to a more human pace. Derec looked from screen to screen, each displaying a different view across the gallery. The crowds bobbed and shuffled as if adrift on water. Then something changed. Derec blinked and leaned closer. It had looked as if a section of the recording had been cut out, one moment spliced to another across the gap left by the missing segment. A subtle jump, heads jerking slightly, and then-

"See?" Kedder asked.

"I'm not -I saw something, but"

"Look," the other operator said sharply. The images backed up, across the gap, and then ran forward again. He rose out of his chair and touched a screen. "Watch this person."

As Derec watched, the gap came, and the person vanished.

"What the-"

"It gets better," Kedder said. "Or worse, depending… watch this screen."

Kedder indicated the middle view which showed the arched tunnel. After several seconds, a crowd of people emerged, marching, boots flashing, black uniforms bulging with armor and adorned by insignia Derec did not recognize.

The other screens changed then. They showed a combination of corridors and alphanumerics. The main gallery was gone, replaced by what appeared to be a military complex. Uniformed figures hurried past, numbers shifted.

"From this point," Kedder said, "we got nothing through the RI that related in any way to what we could see happening down on the floor. While people-while the attack happened, this was all the RI showed. We couldn't get it to reset, we couldn't get it to tell us what was happening. It wasn't responding to any command. Nothing."

"And now?" Derec asked.

"Now it seems to be in positronic collapse."

"All the security-"

"It ran the whole thing. For several minutes before the attack, it was issuing directions for security teams to respond to small crises that we later learned never happened. When the shooting started, most of the security was outside the gallery and all the exits were sealed. We couldn't get the manual overrides to work until it was allover. No data came in, nothing went out, it was as if the entire station had been isolated from all other external systems."

"Which may be just as well," Kedder's coworker said. "If it was having a breakdown, it might have carried over to externals. We might still be waiting for medical and police support."

"But I saw the assault on subetheric."

"Whatever this problem is," Kedder said, "it didn't affect the media nodes the newsnet people brought in that stayed unlinked to the RI. They weren't supposed to do that-everything was supposed to be channeled through the RI for security reasons-but a few always slip unregulated eyes in. Anyway, independent data fed out unimpeded. Only the RI was… diverted."

"And all the security com…?"

"Was being routed through the RI."

Derec stared at the two technicians. "This is impossible."

Kedder looked embarrassed; the other man shrugged.

"What is this it was experiencing?" Derec asked, waving at the screens. "Looks like a simulation."

"A game," the other man said. "Old strategy stuff. It has a number of them in its accessory buffers. Running all the facilities doesn't take up enough of its capacity, so it plays games. It has a terrific chess approach." He pointed to the screen. "This one is called Coup."

"How did it overwhelm the positronic pathways?"

"Beats me, gato."

Kedder frowned at his partner, then said, "Oh, I'm sorry. Mr. Avery, this is Joler Hammis."

Derec nodded briefly.

"Sorry for being rude," Hammis said. "It's been that kind of a day."

"Forget it. So you're running everything manually now?"

"Partly," Hammis said. "We've got a hard programmed back-up helping. It took time to bypass all the systems the RI has-had-direct control of. A few things are run by imbedded hardware and none of that seemed affected at all. There are still functions we can't operate now, like traffic control. All shuttle service has been suspended for the time being, but we have to get that back on-line soon-"

"All right, we can take care of that much," Derec said. "Are the external comlines for the RI open?"

"No, but it's not a problem," Kedder said uncertainly. "Right now it's in no condition to send or receive-"

"Doesn't matter. Is there a place I can work? And patch me into that com system."

While Kedder and Hammis set up a station for him, Derec ran the images back and forth on the screens. It made no sense. It looked almost as though an invasive program had taken over the Resident Intelligence's entire sensory network and fed it false input. But the virtue of positronic RIs made such an invasion impossible. Unlike standard, nonsentient computer systems, positronic brains were not solely dependent on simple digital data input to set priorities. Rather, positronic brains used pre-established, unamendable priorities-the Three Laws, among others-to determine the value of sensory input. They depended on reality as a basis for judgment, reality as perceived through direct sense experience, vetted by hardwired expectations. Data, like that which computer and datum systems used and which told them how to interpret reality, was used only as a secondary reference, without the ability to interfere with the sense-priority nature of the positronic matrix. In this way, the positronic brain was occasionally superior to the human brain-it could not hallucinate, could not delude itself by referencing its own store of experience in isolation from base reality or privileging its experience to supersede its predetermined priorities. In short, a positronic brain could not be subverted. If conflicting information bombarded it to the point where its sense-priority makeup became compromised, collapse occurred. It simply failed.

But this…

"Here, Mr. Avery," Kedder said.

"Derec, please." He looked over the console they had cleared for him. "Good. What I'm going to do is link to the RI at Phylaxis and start load-sharing. Then I'm going to dump the memory buffers of the station RI into our systems so we can start analyzing what happened."

Kedder frowned, glancing over his shoulder. "You can replace our RI with your own?"

"Sort of. It's a temporary arrangement and not nearly as efficient, but it should get all your systems back up and running."

"Well, I suppose that's all right."

Derec hesitated. "Why wouldn't it be?"

"Just that… well, a lot of people blame the RI for what happened-a lot of people here. I'm just not sure how they'd feel about going back to one-"

"Look. As I understand it, you need one to operate efficiently. You can't run the station without one."

"Mainly flight control"

"Fine. Then let me get this set up. Switching to a hard program system will be a lot easier with an RI in place facilitating the changes. Either way, this is necessary."

"I see that, Mr. -uh, Derec. I don't have a problem with it but-"

"Let me worry about the backlash. I'm used to it."

Kedder nodded.

"By the way," Drec said, "what did the robots on the floor do when the shooting started?"

"I don't know. Wandered around, got knocked down by the mob. Nothing useful. See, they're all tied directly to the RI. More efficient to coordinate the entire robotic staff through a central unit-"

"So when the RI started losing touch-"

"It affected the mobile units."

"But their own programming should've kicked them out of the RI's matrix, let them function independently."

Kedder shook his head, a sour expression on his face. "No, they were all deadswitch linked to the RI. Management wanted to be able to shut down all of them from one location. It was easier to simply slave them all to the RI rather than bypass the Three Laws with one single command."

"Slaved through… that would've required patching their sensory modules through the RI sensory net."

"Exactly."

Derec sighed heavily. "In the name of fear and efficiency." He shook himself. "All right, one problem at a time. Have I got direct access to your board from here?"

"Yes. Here and here…"

Derec let Kedder guide him through the basic arrangement until he understood how the systems were integrated, then made a call to Group.

"Rana, this is Derec. We need Thales to sub for the RI here. Let me feed you the parameters."

"Excuse me," Kedder said and walked away to another console.

"Union Station?" Rana asked.

"Yes."