personnel.”
“You’re right, as usual. I just have this horrible feeling that we’re dancing to someone else’s tune, spreading ourselves too thinly. We’ve got Thalia trying to seal the Perigal security hole; we’ve got you and me trying to nail whoever murdered Ruskin-Sartorious; we’ve got the rest of Panoply trying to keep the habitats and the Ultras from cutting each other’s throats. Is it me or is this starting to feel like an unusually busy week?”
“Look on the bright side,” Dreyfus said.
“Thalia’s going to be done soon: that’ll be one case closed. And we’re making solid progress on the Ruskin- Sartorious investigation.” He studied Sparver with sudden intensity.
“We are, aren’t we? Or did you just drop in for tea and sympathy?”
“Tea. For sympathy I go elsewhere. Mind if I use your wall? I want to show you what I got from the router.”
Dreyfus extended a hand.
“Go ahead. It’s group-conjurable.”
With the slightly exaggerated patience Dreyfus had sometimes come to recognise in his underlings,
Sparver walked him through the data. There were five columns of information: the time of arrival of an incoming transmission, its point of origin (the next node up the line), its intended destination (the next node down the line), the time when it had been forwarded—typically only a few nanoseconds after it had come in—and a final column giving some sketchy information concerning the contents of the transmission.
“There’s a lot of CTC traffic coming through,” Sparver said, indicating a proportion of columns with a particular flag in the fifth column.
“That we can dispense with. It’s just navigational housekeeping data, keeping tabs on all the ships and drones moving through the Band.” Sparver removed the CTC data, leaving many blank lines in the wall display. Dreyfus felt cheered: they were getting somewhere. But his glad frame of mind didn’t last long. The remaining data shuffled up to fill the gaps, leaving the wall looking much as it had before. He reminded himself that he was only seeing a small, illustrative portion of the entire router log, and that there were millions of lines above and below the visible segment.
“Now we do a similar filtering on polling traffic,” Sparver said.
“That takes care of another major chunk of the data. Run the same trick on traffic on the major trade nets and we delete another big chunk. It may not look like an improvement, but we’ve already shrunk the log by about half. But we can do better still. Clear out all router housekeeping and we drop another ten per cent. Clear out standard abstraction packets and we’re down to about twenty per cent of our original file.”
It must still have been tens of thousands of lines.
“We’ll need to do better than that, even,” Dreyfus said.
“And we can. Now we filter on the target address of Ruskin-Sartorious.” Sparver scrolled up and down to show that he had now reduced the log to a mere thousand lines or so.
Dreyfus scratched at his left eyebrow.
“Why didn’t we just jump to this point in the first place?”
“Doesn’t work like that,” Sparver said.
“Like almost every habitat in the Glitter Band, Ruskin-Sartorious would have handled onward forwarding of third-party data, including CTC services, trade talk, abstraction packets, the works. We’d still have had to strip all that from the list even if we narrowed it down to messages only going to Ruskin-Sartorious.”
“Would have been faster, though.”
“But logically equivalent. The system doesn’t care in which order you do the filtering.”
“I’ll take your word for it. But we’re still looking at a mass of data.”
“We’re not done. Now we start getting clever.”
“I thought we were already being clever.”
“Not enough.” Sparver smiled—he was clearly enjoying himself.
“See that number in the fourth column?”
“Yes,” Dreyfus said guardedly.
“Timetag for outgoing transmission.”
“That’s our clue. The message that came through to Ruskin-Sartorious was voice-only, right?”
“According to Vernon and Delphine. What difference does the message format make?”
Sparver drank from his cup.
“It makes a world of difference. When a transmission goes through the router, it’s subjected to a certain amount of routine processing. Cyclic redundancy error-checking, that kind of thing. If there’s a fault, the router sends a message back to the previous sender, asking for a
repeat transmission.” Dreyfus nodded provisionally.
“Makes sense.”
“The point is, all that error-checking takes a finite amount of time. And the heavier the data burden—the more content there is in the message—the more number-crunching needs to be done.”
“Ah. I think I see where you’re going.”
“The key’s in the outgoing timetag, Boss. Compared to most of the traffic the router would have forwarded to Ruskin-Sartorious, voice-only comms are hardly worth mentioning. The processing delay would have been almost zero.”
“So when the time difference between the incoming and outgoing tags is smallest—”.
“We’ll probably have isolated our message. Or at least some possible candidates.”
“Do it,” Dreyfus said excitedly. Sparver was ahead of him. Now the wall showed only a dozen transmissions, all falling within the likely interval when Delphine had been warned to break off negotiations with the Ultras.
“We’re still not down to one—” Dreyfus began.
“But we’re getting damned warm. Now we can apply some good old intuitive police work. We look at the originating nodes. Check out the second column, Boss—I’ve resolved the addresses into recognisable names. Now, I’m willing to bet that most of them will correspond to habitats that have either been in contact with Ruskin- Sartorious over a long period of time, or which are places we’d expect to broadcast to the entire Glitter Band on a fairly regular basis.”
“Can you check that?”
“Already did. You ready for this?” Sparver sent a command to the wall. Now there was only one transmission entry left.
“You’ll need to look over the eleven I rejected, but I’m pretty confident we can rule them out. This one, on the other hand, sticks out like the proverbial.”
“In what way?”
“The point of origin isn’t anywhere I recognise, which immediately sets off my alarm bells. It’s just a rock, a free-floating chunk of unprocessed asteroid drifting in one of the middle orbits.”
“Someone’s got to own it.”
“The claim on the rock goes back to a family or combine called Nerval-Lermontov. Whether that means anything or not, I don’t know.”
“Nerval-Lermontov,” Dreyfus said, repeating the name slowly.
“I know that family name from somewhere.”
“But then you know a lot of families.”
“They could be innocent. Is there any reason to think this rock isn’t just another router?”
“Maybe it is. But here’s the odd thing. Whoever made the call, whoever sent that signal from the Nerval- Lermontov rock—whether it originated there, or was just routed through it—that was the only time they ever contacted Ruskin-Sartorious through that particular node.”
“You’re right,” Dreyfus said approvingly.
“Alarm bells. Lots of them.” Sparver put down his tea, the china clinking delicately against Dreyfus’ table.
“Never say we pigs don’t have our uses.” A flying horse had been waiting for Thalia when she arrived in the Chevelure-Sambuke Hourglass. The animal’s wings beat the air with dreamlike slowness, slender legs treading air as if galloping on the spot. Its skin was transparent, affording an anatomically precise view of its tightly packed internal organs, its highly modified skeleton and musculature. The insectile wings were blade-slender, intricately
