Her visor flashed, and she sped up her subjective perception again. It was time. She left a note on the couch saying 'BRB' and a recorder bug so she wouldn't miss anything Journeyman was saying if she was gone for more than a word or two, then broke through the thin layer of plastic she'd placed over his doorway as a compromise between avoiding property damage and keeping out the cold air. She rounded the corner of his modest rural home and workshop, and headed out.
Jetgirl had a secret power.
Everyone knew about her jetpack, and her flightsuit wings. Most had heard of her telescopic goggles, and her 'Zap Gun'. Her fans, and there were a fair number, knew about the variety of equipment she carried on her utility harness, and that she was a superb forward observer, in the specific military meaning of the term. They also knew she had something extra, something special for dealing with really tough foes, out where there wasn't any chance of collateral damage, and, frustratingly for them, rarely any nearby witnesses.
The most popular theory was that she had some kind of heavy plasma cannon mounted on a truck driven by an assistant, kept it quiet because the authorities tended to frown on that sort of thing, and would lure opponents into its sights. But no one had ever seen it, so speculation continued.
In truth, it was a matter of being willing to do a lot of preparation and calculation in midair, and fly in a way that looked just clumsy enough, that surely the next shot or lunge would get her. Until her opponent–in this case a giant, magically animated, flying skull that fired energy beams from its eyes–was in a position where no debris would cause damage or injury when something specific happened.
Then she called Flicker.
And Flicker was willing to come when called, even when she was off duty, even when she'd been asleep. Because not only were they good friends, but she trusted Jetgirl to take care of all the details–especially the one about making sure there was a safe place for any wreckage to fall.
So all Flicker had to do was show up. And throw rocks. And then go right back to whatever she'd been doing, knowing she'd done something worthwhile and helpful for a friend, all in a few seconds.
Jetgirl was several states away, and High Speed Pathing had shown many of the highways as clogged with traffic, but there was a rail line handy, so Flicker followed that, picking up a few likely rocks from beside the tracks as she went.
It wasn't an emergency, so Flicker didn't go faster than 0.05 c. The locomotive engineers of the trains she passed by or over saw a flash of light and heard a peal of thunder, but the trains themselves were barely buffeted. In ninety-one milliseconds she was at the specified coordinates–in the middle of a stubble filled field–and looked up along the vector to find the skull. There it was, about two kilometers up, frozen in its midair ballet with Jetgirl, who had accelerated away to a safe distance off to the side before calling.
Flicker increased the magnification of her visor to get a better picture, and updated the position and velocity data on the skull, noting Jetgirl's estimate of its mass and internal structure. The wild card was the force field she had warned about, glowing a faint sullen red around the skull. Jetgirl's Zap Gun and grenades hadn't been able to touch it. She planned her first rock with that in mind.
It was a nice quarter kilo chunk of stone, and Flicker threw it at about 200 kilometers per second, an order of magnitude faster then the average meteor. The explosive energy equivalent would be a little over a ton of TNT, about the same as a shell from a battleship gun.
There was a thin line of light along the flight path from where Flicker was standing, a flash of light as it hit, a slight brightening of the force field in the area around it–and otherwise nothing. It hadn't dropped the force field, or gone through. There would be a boom eventually, but Flicker wasn't going to stand around and wait for something as slow as sound waves to arrive.
She sent the second rock on it's way at 600 kilometers per second, about ten tons of TNT equivalent. A brighter line, a bigger flash, a larger area of force field brightening–but still no penetration.
Fine. So it had a strong force field, one tuned to reflect most of the energy and prevent point penetrations. It was probably easier to overload over a longer time–cooling would be a serious problem if nothing else–but Flicker wasn't about to wait. Not when she could just throw the next rock harder.
Third rock, 2,000 kilometers per second, 100 tons equivalent. Jetgirl would definitely feel the shockwave from this one, even at half a kilometer away. But her suit had ear protection, and she was facing away and accelerating, she knew the drill. Flicker watched the rock hit, the bright flash much larger than the skull now. The whole force field wavered, glowing intensely–and held.
Okay, this was starting to get silly. She double checked the location of the nearest houses and vehicles. Some of them were going to get broken windows. She also sent a flash warning to Jetgirl, who was going to have one hell of a ride. Flicker estimated how far away she would be when the shockwave from the next rock hit her, and corrected for her velocity. She should still be okay, she'd had worse.
Flicker made sure her data recorders were capturing everything, Doc and Journeyman would want to see the telemetry from this. Ideally they'd want to inspect surviving pieces of the skull, too, but there wasn't going to be any.
Flicker threw the fourth, slightly heavier rock at about 6,000 kilometers per second, two percent of the speed of light, and it released a kiloton of TNT's worth of energy when it hit.
That, finally, was enough. The skull disappeared in the fireball–and didn't reappear afterwards.
She stayed long enough to watch Jetgirl resume controlled flight after the shockwave hit, and send an apology, then headed back.
Flicker had been gone a little over two seconds, most of it making sure Jetgirl was going to be okay, when she returned to Journeyman's workshop. She took a moment to replace the plastic over the door, then checked the feed from her recorder bug. She'd missed the words '–not her fault.' and Journeyman was just looking up and frowning as he realized she'd disappeared when she returned to her seat on the couch.
"Sorry," she said. "Took a little longer than I expected. But go on. Not her fault–why not?"
"Because," said Journeyman, "if she's too specific about what she sees in the future, her ability to affect it will stop working. And if she is specific only some of the time, people would be able to tell when she's predicting and when not. So it's probably a safety habit."
"Ah, okay. It's still irritating. Especially when I want advice about the present that depends on general principles rather than specific predictions."
"Yeah, I can see that." He raised an eyebrow. "So are you going to tell me where you went?"
"Nebraska. Jetgirl needed a hand taking out one of those giant flying skull things."
"A Necrocap? How big was it?"
"About five meters tall or so. I'm not sure whether that's big for one of them or not–Database didn't have any specific size data."
"That's huge. I wonder who made it, and what they fed it. They're really dangerous, because they have an impenetrable force field that's–"
"It's not impenetrable."
"Well, yes, but you have to use a trick to–"
"Nope, I just threw rocks."
"I suppose hitting it from more than one direction at a time would–"
"Same direction. Took four rocks, upping the energy an order of magnitude each time."
Journeyman stared at her for a moment, and she could see him calculating in his head. "Um. Just how hard did you throw the last rock?"
"At 0.02 c. Yield was about a kiloton. No one got hurt, because Jetgirl did a good job of luring it high up and way out in the countryside, but there will be a few broken windows, and it will probably make the news. Oh, and Jetgirl will be sore tomorrow from the shockwave, even with the protection from her suit. She was only half a kilometer away."
"You know, I could have given some useful advice on how to handle it, if you had stopped to ask me."
"You know, I wouldn't have to stop to ask you for advice, if you'd recorded some of this important information on fighting giant flying skulls in the Database, where it belongs. And where I can access it at high speed. Jetgirl might have found it handy, too. I didn't even know you were an expert."
