Arc Riders

by David Drake

  She was right, of course. Roebeck’s electromagnetic pulse hadn’t hurt the revisionist, just shut down the controls of the engine that kept him stable in the gusty wind currents. He’d had nearly thirty seconds to scream as he tumbled down toward water which was rock-solid at the speed he hit it.

  Barthuli found displacement suits interesting, the same way he was interested in Acheulean hand-axes. The analyst’s unworldliness was deceptive, though. In a crisis, he could react as quickly as a switch makes contact. The trouble was that with Barthuli, you could never be sure how he would react.

  Dor Jalouse was the team member who’d loved his suit for the power and anonymity it gave him. No ARC Rider could be lazy or stupid, but Dor was something of an underachiever. He would use the suit’s systems to access information just to save physical effort, and he took a childish pleasure in walking through closed doors in his armor. He always completed his tasks, though perhaps close to the deadline, and he knew his systems almost as well as Chun knew hers.

  Dor Jalouse would have been the perfect Rider to be on external guard right now. Unfortunately, he was lost, and—as Grainger had said—lost forever. When Roebeck corrected the revision, she would saw off the branch of time to which Jalouse clung.

  The grass in this valley was still green, though the beeches scattered in clumps had turned largely golden. The team had been lucky when TC 779 displaced. Another blizzard would make work on the capsule difficult.

  There would have to be work. The plasma bolts had flayed off three square meters of the outer skin forward of the hatch. Some, perhaps all, of the electronics in that section of hull would be damaged.

  The emergency displacement had seemed normal, but that didn’t prove anything. Most of the spatial circuitry lay along the inner hull while the temporal hardware was attached to the outer skin. Until Roebeck knew where the program had intended them to land, she couldn’t assume that even the spatial portion of the equipment was working properly.

  Grainger stepped from the vehicle, graceful despite the burden of his armor. He’d used the suit’s load-carrying ability to add a tanglefoot projector and a plasma weapon to his armaments.

  “I’ve got the duty, Nan,” Grainger called cheerfully on the intercom. He hopped to the top of the outcrop beneath which she’d sheltered.

  Rather than set his suit as Roebeck did to highlight movement all around him, Grainger simply raised the magnification a moderate degree and turned his head constantly. The sensors had an alarm function that would flash Grainger a vector to anything the suit’s artificial intelligence believed was threatening, but the triggerman had no intention of trusting a machine to do his job.

  “You might echo the main screen,” Roebeck suggested as she headed back to the capsule. “If nobody’s appeared by now, they probably can’t track us. Judging from the timing, I suspect they homed on the displacement suits’ wake.”

  “Assuming our sensors are all working and the hostiles aren’t hovering just out of phase, waiting for an opportunity,” Grainger said. “You check on what happened back there, chief. I’ll stay here and make sure it doesn’t happen again.”

  Roebeck wanted Grainger’s eye—a very good eye indeed—to go over the recording of the attack on the capsule. He was right, though. There’d be time for that later, when they were sure that TC 779 was capable of spotting hostiles lurking a few angstroms from the present. Until then, Grainger’s whole attention should be on the safety of the capsule and the surviving team members.

  Roebeck lifted her faceshield when she entered the cabin. The atmosphere had a burned tinge which she hadn’t noticed before. She hoped that didn’t mean a bolt had penetrated both hulls.

  Chun noticed the pinch of Roebeck’s nostrils. “One of the osmotic exchange panels was damaged,” Chun explained. “I didn’t notice the telltale in time to shut it off before it had started shifting ozone. We’re over capacity, even…”

  Even with one panel removed, the capsule’s air system could provide enough oxygen for a full crew of six. From the way she’d failed to finish the thought, Chun must have wondered whether Weigand’s trio was now as completely lost as Jalouse was.

  Chun looked up with concern hidden beneath a mask of calm. “I don’t think the revisionists we’re after were responsible for the attack, Nan,” she said.

  “Well, I didn’t expect that they were,” Roebeck said as she slid into the seat from which she could most comfortably watch the display. “Granting a suit displacing makes more of a blip than a capsule does, it’s not much of a blip. It’d take apparatus as sensitive as Central’s to target us that way.”

  “Yes,” said Chun simply as her wands dipped. “Central has sent a team of ARC Riders. To stop us.”

  The display brightened into an enhanced, slowed-down image of the attack. The computer projected a three-dimensional hologram in which TC 779 was the center of the scene. The information displayed was melded from sensor recordings, enhancement, and backgrounds stored in the database itself.

  A second transportation capsule winked into existence ten meters from TC 779, just beyond the “patio” Roebeck’s team was clearing of snow. The intruder hovered a meter in the air. Differences in design between the attacking craft and a 700-series capsule from the team’s timeline were too slight to note with the naked eye, even though Roebeck had seen them highlighted when she went over the recording of their entry into the wrong Central. A hatch in the center of the vehicle blinked open.

  Two figures waited with weapons shouldered in the hatchway. Their armor flared at the joints but was otherwise identical to the team’s own displacement suits. Their weapons slashed incandescent tracks toward the hull of TC 779.

  The capsule wasn’t in a posture of defense, but the standby magnetic shielding instantly shot up to maximum density. Plasma repelled by the shielding splashed off like water being hosed against a smooth boulder. Snow flashed to steam. Grass and even the turf itself, rich in organic compounds, erupted in smoky red flame.

  The plasma, nitrogen atoms stripped of their electron shells, was of minuscule mass. Accelerated to nearly the speed of light by positively charged coils in the fat barrel, that mass caused the weapon to recoil violently.

  Instead of firing short bursts, the two figures kept their fingers on the triggers. The gun muzzles lifted; their streams of hellfire exploded deep trenches across the snowbound prairie. Momentarily a third plasma weapon fired from knee-level behind the two standing figures.

  “Lousy technique,” Rocbcck muttered. If the gunmen had pulsed rather than streaming their plasma, and if they’d both focused their bursts on a single aiming point—the hatch was the obvious choice—they’d have holed TC 779’s cabin and incinerated its occupants before Roebeck could displace.

  “What?” Chun asked.

  “If they were my people, I’d burn them both new assholes,” Roebeck said. “Can you imagine Grainger and Jalouse letting a target like that get away? We were fish in a barrel, and they missed us.”

  “You’re offended by a murderer’s bad craftsmanship?” Chun asked coldly. She didn’t comment on the fact the error had been committed by the team’s enemies. That didn’t affect the moral question.

  “Sure I am,” Roebeck said. “We work for the ARC, remember.”

  “Not this one!” Chun snapped.

  Roebeck shrugged. “If it could happen here, it could happen to ours. But not to my people.”

  Chun’s tight mouth suddenly broke into a broad grin. “Yes,” she said, “I’m shaky from what happened, too…. But I prefer to cling to a myth of universal human decency rather than one of invincible skill in a crisis.”

  Roebeck choked, then bent as a gust of laughter clamped her ribs. “Quo, I swear by every god I’ve come across in fifty missions, I’ve never been closer to the hostiles handing me my head. And it’s my own fault. I should have known that we’d have Central on the other side. What we’re going to do is a revision from where they stand, after all.”

  �
��We were thinking of the group from the 23d,” Chun said. “Gerd probably realized that the new timeline’s ARC Riders might take a hand, but he must not have known that Central could track suit displacements. Otherwise he’d have said something.”

  Her face went still as she considered what she’d just said. She was suddenly less certain of the statement than she would have been if some Rider other than Barthuli were the subject of it.

  “Sure, he’d have said something,” Roebeck said. “We don’t know that the hostiles can really track the wake of displacement suits, either. They spotted the point of displacement, but that doesn’t mean they followed Weigand to wherever he was going.”

  The greatly slowed action on the display came to an end as TC 779, a patch of its hull glowing, vanished from the image area. As a coda to the recorded event, the capsule’s computer postulated a doughnut of vaporized hull metal continuing to lift on the heated air.

  “Let me offer an argument for humane behavior,” Chun said, flicking the recording backward by jumps. “How would you have arranged an attack like this, Nan?”

  Roebeck pursed her lips. “Full team?”

  Chun nodded. She’d stopped the display about midway in the attack.

  “Jalouse and me in the port with EMP generators,” Roebeck said. “If the target isn’t shielded, it’s fried and harmless. If it’s got magnetic shielding, and I’d assume it did, the generators are still more efficient against a given flux density than plasma at the range in question.”

  “And EMP generators have a broader field,” Chun said.

  “Right,” Roebeck agreed. “Jalouse and me jump from the hatch, clearing it for Weigand with a plasma weapon. His size helps stabilize the recoil. And Grainger with the fléchette gun he favors—I want a mix of stimuli hitting the hostiles as quickly as we can. We don’t know what their defenses are, even if the capsule does look a lot like one of ours.”

  “Tim would complain about being in the second wave,” Chun said, acting as the Devil’s advocate.

  Roebeck shrugged again. “The first two use EMP generators because we can jump clear of the follow-up pair while using them. As you said, the pulses are a broad cone. There’s no way to aim a high-recoil weapon with useful accuracy while you’re leaping through the air.”

  Roebeck grinned wryly. “Barthuli’s backup with another plasma gun,” she concluded. “I’d say an EMP generator, but Dor and I’d be in the cone if he had to use it. And you’re at the capsule controls.”

  “A good decision,” Chun said expressionlessly, “as I’d expect from you. Now, look at what the hostiles did.”

  The display froze on the hatch of the attacking vehicle and changed scale downward. As the image expanded to approach 1:1, the figures in the hatchway lost individuality. The computer was enhancing detail beyond the limits of the recorder’s resolution.

  “You would be willing to kill on an operation of that sort,” Chun said. Her wands moved and outlines resolved still further. Two more armored figures sharpened from the shadows within the cabin.

  “Yes, I would,” Roebeck said. She had her morality, Quo had a different one. That was life. “I’ll kill now if I have to.”

  The hostiles behind the first pair also carried plasma weapons. Roebeck remembered the brief pulse somebody had fired between his fellows’ legs. With hardware as notoriously difficult to control as a plasma weapon, the shooter was lucky his burst hadn’t cut down one or both of the personnel in the hatchway.

  “But that wouldn’t be your first priority?” Chun prodded. Her wands let the scene crawl forward. The hostiles began firing, but the pair behind them were crowding the shooters for room to aim their weapons. “Killing, I mean?”

  “Good God, no!” Roebeck said. “First priority is always the mission. Even for Tim. It’s just that, you know it yourself, Quo. Sometimes things can’t be as clean as you’d like them to be.”

  “It’s easy to be moral when you know somebody else will pull the trigger for you, you mean?” Chun said.

  “I didn’t—” Roebeck said.

  “Then you should have,” Chun interrupted harshly. “Because it’s true, and I know that as well as you do.”

  Chun took a deep breath. “But look at the hostiles,” she went on in a settled tone again. She flicked her head sideways to indicate the display. The control wands prevented her from making normal hand gestures.

  It wasn’t just recoil that threw the plasma beams into a crazy-eight. The pair of hostiles inside the cabin was actively jostling the shooters in front of them.

  Roebeck watched, this time in full detail, as one of the backup team dropped prone to get a shot. Plasma began to scatter as soon as it left the muzzle, so even the half-second the third weapon fired was enough to overload the environmental systems of the pair in the hatch.

  “They went berserk,” Roebeck said. “Just like the clerks or whatever in the transfer room when Jalouse walked in. They had us cold, and they didn’t nail us because they wanted to kill so bad.”

  “Barthuli may think the revised timeline is almost identical to ours,” Chun said. “I think there are points of distinction more significant than coincidental likenesses of vehicle and room design.”

  That was closer to open confrontation than Roebeck had ever expected to hear from Quo. The fact Barthuli wasn’t present to hear the statement was beside the point: Quo wouldn’t say anything behind a person’s back that she wouldn’t say to his face.

  “You know…” Roebeck said aloud, “I think Gerd would probably agree with you.”

  She should have said, “will agree.” She couldn’t give up hope for the trio’s safety, not yet.

  “I checked the arms locker,” Chun said, answering the question just forming in Roebeck’s mind. “Pauli took a projector with a mix of gas and tanglefoot rounds. The others have only the acoustics in their integral survival pouches. They weren’t expecting trouble.”

  Roebeck swore softly. It was all up to Weigand’s trio if they returned while the hostile vehicle was still at the North American 50K site. Acoustics and gas shells would be useless against hostiles in armor. The tanglefoot mixture could net and hold against even a displacement suit’s powered muscles, but chances were there’d be more than one target to deal with.

  Pauli might be fast enough…. But he might not even realize the waiting vehicle wasn’t TC 779.

  “Perhaps they’ll displace again,” Chun suggested.

  “Carnes won’t be able to, not fast enough,” Roebeck said. “She probably won’t know there’s a problem. Barthuli…”

  She smiled grimly. “I’m not sure Gerd would even try to escape. There’s a whole new timeline for him to explore, after all.”

  “They might kill him out of hand,” Chun said. “They probably would.”

  “Again,” Roebeck said, “I’m not sure Gerd would care.”

  She closed her eyes and forced herself to imagine the battle that might be taking place now, only a continent away. “Pauli could escape. If he was alone, that’s what he’d do. But I made him responsible for the other two.”

  Roebeck leaned the seat of her console back so that her eyes opened to the cabin’s familiar ceiling. “On the good side, I wouldn’t stick around the site of an attack where I’d let the targets get away. That’s the one place they—we—know they are to hit back. But as you pointed out, I don’t think like their team leader.”

  “Nan?” Chun Quo said quietly.

  Roebeck turned her head toward her.

  “We’re shorthanded now,” Chun said. “We may have to do things that usually there’d be somebody else to do.”

  She placed her control wands carefully into the holder in her chair arm. “I can administer antibiotics to disease bacilli,” she said. “And in this case, I can do whatever is necessary to save our timeline.”

  “You think shooters as good as Tim and me’ll want you getting in the way?” Roebeck said. The only way to handle Quo’s offer to compromise her honor was to turn it i
nto a passing joke. “But I’ll keep your application on file.”

  She coughed to clear her throat. “Now let’s see what we’ve got left in the way of a transportation capsule.”

  “We don’t have temporal capacity at the moment,” Chun said, “but I think that’s repairable. If we—”

  “Hold on,” Roebeck interrupted gently. She spread the intervals between keys so that she could use her board with gauntlets on. “First things first. I want to know whether we can spot the hostiles if they wait out of phase.”

  It took her a minute to bring up a three-dimensional graphic. It showed magnetic and optical anomalies in a hundred-meter circle of the capsule during the period since they’d displaced here.

  “We can’t check our sensors without another set to compare their data with, can we?” Chun said in puzzlement.

  Time and space are relative approximations rather than constants. At no two points in space or time is the velocity of light, for example, precisely the same. By cataloging the local pattern of variation, the transportation capsule’s computer could determine—by relatively gross changes in the flow—that another vehicle was nearly in phase with their horizon.

  But that presupposed TC 779’s sensors were still giving readings accurate at a sufficient level of subtlety.

  “We can check what we’re receiving now against similar time slices from before the attack,” Roebeck explained. “The raw data won’t be the same, but if the pattern is the same, then we can be reasonably sure that our robot friend here will warn us if somebody’s peeking to line up an attack.”

  “If I’d thought of that,” Chun said, “I could have done it myself.” And faster by a good deal. “But I didn’t think of it.”

  Roebeck grinned, aware both of the flattery and the basic truth beneath it. “Take a look and tell me what you think,” she said.

  Chun lifted out her wands. Instead of using a separate mini-screen, she echoed the data on the main display. She color-weighted four graphs, averaged each separately, and projected the totals as individual quadrants of the display. All four were in the yellow-green/middle-green range.