A/N: This will be darker than Thunderbirds Are Go, in that the death toll will be nonzero. This will also be lighter than StarCraft, in that the death toll will remain below the billions. I make no promises beyond that.

"John," asked Virgil, "why is there mud down here?" A highly perplexing question, given that 'down here' was beneath a rapidly crumbling skyscraper, in extremely dry weather, nowhere near any fluid mains, well above the water table.

"Virgil," said John, "that's not mud. And it's not the classic not-mud joke either. Beyond that, I don't know. Your suit doesn't have the scanning ability to find out."

"Should I take a sample for Brains?"

"If you have time."

"Should only take a second." Virgil bent down to scoop up some not-mud in the powersuit's grasping claw. "Or maybe not." The stuff didn't want to be scooped up. He tried again, with more focus, to exactly the same result - it just slid off the claw. "Okay, I'll have to do it later."

John slipped back into command mode. "The second pillar you need to reinforce is thirty metres away, bearing three-four-zero."

"On it." Virgil picked up the drum of stabilising foam again and carried on. "How's the evacuation going?"

"Sixty percent complete. Gordon and Alan are making good time with Thunderbird Two."

"If they get one scratch on my 'Bird..." Virgil muttered to himself.

"And don't they know it. Focus on your mission."

"Yes, John. Take the fun out of everything, why don't you?"

"Hang on." John went silent for a moment, presumably checking detailed instruments on Thunderbird Five. "EOS reports possible life signs in your vicinity."

"Life signs? Who would be down here?" Virgil looked around for a moment from spraying stabilising foam into a cracked foundation pillar, trying to spot hiding places, then continued "And where would they be?"

"No idea - they're so faint I can't localise them at all. EOS only just picked them up."

"Well, neat. I'm done with the second pillar now; moving to the third. Tell me if they get any more localised."

"I'll send Scott down to help if you'd like."

"No thanks, he's no structural engineer and we both know it."

"I meant scanning for lifesigns."

"After the main evac is complete. Needs of the many."

The main evacuation was going surprisingly well. Thunderbird Two, piloted by Gordon and rescue couch manned by Alan, rapidly relocated people to surrounding open areas from where they could be moved to safety. Scott had left Thunderbird One parked somewhere safe and jetpacked into the building to find and assist stricken evacuees; at that moment, he encountered a small mass of people trying to move a metal beam off a trapped man.

The man looked up, then his eyes widened. "Thank God!" - an understandable reaction when International Rescue appeared.

"Better, thank Thunderbird Five." The throng parted for Scott, who set to work. "Now, that beam's not bearing any load, it's just heavy. Stay still on three, I'll try to cut through it." (The throng moved various limbs a little further out of the way.) "One. Two. Three! ...There. Lift it now!"

The smaller segment of metal beam moved more easily, and the man was soon free.

Scott didn't stop to receive thanks. "The ground isn't safe - it's subsiding already. All of you, get to the nearest stairwell and go up to the roof. Thunderbird Two will get you to safety." And he was gone, headed to the next trouble spot.

[[Scott,]] EOS piped up in his ear, [[the north-west evacuation stairwell is empty below the ninth floor. I suspect a blockage.]]

"Copy, EOS, moving to eighth floor to investigate." Scott activated his jetpack and exited through a shattered window.

"John, there's more not-mud here, and it's blocking the whole route this time." Virgil frowned. "I might have to walk through it. ...Scratch that, I will have to."

"Confirmed; there are no other routes to the next pillar. Be careful."

"You mistaking me for Scott now? ...Oh. Oh. John, we may, have a problem. It's, slowing me down. Rather a lot."

"Mud does that, Virgil. Even I know that much."

"This isn't, like mud. It's worse. The stuff's, sucking my feet down, and then resisting when, I pull them out. Hard. It's like it was, designed to slow, people. Ah good, here's the other edge. And the pillar too. Heard anything more from the weird life signs?"

"They were stronger just then," John said, puzzled, "but now weaker."

"Oh, no. What if they're submerged in that slow-soup?"

A wave of revulsion flowed over John just as it had over Virgil.

Scott lasered through the locked stairwell door on the former ground floor, dramatically kicked it open (people seemed to wake up a bit when he dramatically kicked doors open), then bellowed behind him, "It's clear! Move up! Thunderbird Two will get you out from the roof!"

"Thank you, International Rescue!" was the gist of the response.

He sighed and leant against a stable-looking wall to use his communicator. "Thunderbird Five, I've evacuated what used to be the ground floor. Is there anyone below me?"

[[Negative,]] EOS reported. [[Basement levels appear unoccupied. There is a clear signal from Virgil in the foundations, but no other life signs.]]

"Do I have time to check anyway?"

[[Affirmative.]]

Scott scurried down to the basement levels. The first two were clear of all life - he checked twice to make sure. The third was also clear of all life, but in a less mundane fashion.

"Oh, man. Virgil, this is bad. Basement level three is half fallen away. Watch out down there."

"Says you."

"Thunderbird Five, are you getting this?"

"Affirmative." The news was serious enough to warrant John's attention. "I have no idea how that happened-"

"Worry about it later!" said Scott, snapping into full command mode. "We need to speed this up. Thunderbird Two, what's your status?"

"Almost done," Gordon reported, as Virgil suppressed the urge to respond for him. "The group you just sent up is the last lot we're waiting on. As soon as they're out, we're gone, and the controlled demolition crews can take over this time-bomb."

"Got it. I'm going to help Virgil-"

"Aah!" said Virgil, and activated his distress beacon.

"-right now!" Scott activated his jetpack and descended through the ruins of basement level three towards him. "Virgil, what's happening?"

Radio silence.

"Virgil!"

Radio silence.

"Virgil, do you read me?!" Scott screamed, closing on Virgil's last known location.

To his immense relief, Virgil was still there. To his horror, so was a barely-human-looking corpse in several pieces.

Scott stared at Virgil. Virgil stared at the corpse. The corpse stared at oblivion. Oblivion stared at Scott.

Then the not-mud beneath the corpse boiled up, absorbed it, and receded again.

"Virgil," somebody said very quietly, "what the hell happened?"

"I don't know," said Virgil presently, after several deep breaths. "She just-" Without warning, he activated his helmet's emergency release, threw it behind him (Scott barely caught it), vomited onto the patch of not-mud where the corpse had been, then fell forward onto his kness, barely avoiding the resulting mess. "She just tried to tear me apart, Scott." He dry-heaved. "I tried to stop her, but she - I caught her arm, but she tore it off!" Understandably for even a seasoned first- and second-responder, Virgil was now sounding a bit manic. "She tore her own fucking arm off!"

That explains the severed arm in the powersuit's grip, Scott thought grimly.

There was a gurgling sound. Several similar barely-humans emerged from the darkness, walking on the not-mud as if it were concrete.

Nobody said anything for a few seconds, fixated on the shambling horrors.

"Scott," John eventually said, "shoot to kill."

With Virgil still immobilised in shock and basically a group of zombies advancing on him, Scott was not inclined to disagree. His laser cutter made a decent improvised weapon at full power, and the approaching zombies were each soon cut into several pieces that weren't a danger to anyone.

There were several moments of silence for whoever they'd been before International Rescue leapt back into action.

[[Attention. None of the assailants showed up as lifesigns,]] EOS reported, as what was left of said assailants was eaten by the not-mud. [[Life readings in the area are still unexplained.]]

"So anything could be lurking down here," Scott whispered, trying to reassure Virgil, which at this moment involved Virgil not hearing him. "Great. I feel like we've walked into a horror story."

"We might as well have," Virgil sighed, clearly having heard him anyway. "I am so out of here."

"Guys!" John sounded more energised now. "I've got two lifesigns in your area."

As Virgil hastened to stand, EOS turned the mood straight back to horror. [[Alert! They're not human! They're moving too fast! On your left!]]

Scott turned to look, and two overgrown roughly-dog-shaped hellspawn leaped out of the floor at them. Well-drilled Air Force reflexes brought his laser cutter to bear and one of the whatever-the-hell-they-were crashed to the ground. The other leapt onto Virgil and knocked him flat on his back.

As Scott and Alan had learned in Thunderbird Three's altercation with the Mechanic, a grappling fight was all about the number of limbs you had - the more, the better. Virgil, freed of the need to stand, had four, only two of which ended in useful manipulators, and only the same two of which he was in any way adept at using. The hellspawn had at least six, four legs and two other appendages, each with claws or spikes, and it appeared to have mastered them all. In addition, the hellspawn had seemingly been sculpted for combat. Virgil had the powersuit, but it was hardly combat equipment; not suited for resisting or dealing damage to something this resilient and deadly.

Scott swiftly determined it wasn't safe to laser the melee from range; the risk of cutting Virgil apart was too high. He advanced, ready to-

"Scott! The other one's still active!"

Thank you, Thunderbird Five, Scott thought (for once without a hint of sarcasm), turning back to the hellspawn he'd crippled earlier. The laser cuts were already healing, and it was silently dragging itself towards him. He cut it some more. And then some more. And then some more. This thing needed to be thoroughly dead, now.

Finally satisfied it wouldn't be getting back up, he ran back to Virgil, who was losing. Half a second of indecision allowed the hellspawn to gain the upper hand moreso than it already had. Then he came up with a plan. It was a typically risky Scott Tracy plan. Oh well, I'll reflect on that if we're both alive at the end of this, he thought, and leapt onto its back, pressing the laser cutter's barrel against the back of its neck and making a short cut - he couldn't risk cutting too far for fear of overpenetrating and hitting Virgil, but it still got the thing's attention, and its other limbs (tentacles? no, too rigid) came down to stab him in the back. Had he not been wearing his jetpack, the wounds would have been fatal. As it was, the jetpack was totalled, which was thankfully the extent of the damage to Scott. On the other hand, one of the spikes penetrated the power cell in the jetpack.

The results were dramatic - those powerpacks were both almost impregnable (which spoke volumes about the power of the spike and the limb bearing it), and very explosive when breached. The directed explosion might have caused appreciable damage to the spike - nobody was paying attention - but it definitely overwhelmed even the hellspawn's extreme pain threshold. It flinched and withdrew for a second. That was the opening Virgil needed to turn the tide. Summoning his last reserves of adrenaline, he threw the hellspawn off him. Scott combat-rolled to the side to avoid being crushed, still laser-cutting as much as he dared. Virgil dived forward, caught the powersuit's still-functioning spreader arm in a wound in its upper neck, spread it, and then stabbed and stabbed and stabbed until the thing finally, blessedly, stopped moving.

It was only now that the extent of his wounds caught up to him and he collapsed on the thankfully untainted ground. Adrenaline was pretty handy.

"Oh. Oh gods." Scott, relatively unharmed, discarded the ruins of his jetpack, then fought a similar instinct to collapse and checked on Virgil. "John, call Thunderbird Two back. We need to get Virgil to a hospital pronto."

"Thunderbird Two has completed its mission and is en route. They'll be down in pods soon."

"FAB. I'm patching Virgil up as best I can."

[[Warning,]] said EOS. [[Scanner calibration has revealed six similar lifeforms in the area. Remain on your guard.]]

"Great. Just great. C'mon Virgil, stay with me."

[[Warning. Additional unidentified lifeforms detected in the area. I recommend immediate evacuation.]]

"What, worse than the others?"

EOS managed to sound scared. [[Bigger.]]

"Scott," said John, "this is past our pay grade. I'm calling the GDF, and notifying Alan and Gordon to armor their pods."

It was three minutes later, with Virgil relatively stabilised and ready to move, and the pods not long away, that EOS announced their doom again. [[Alert. Additional ...hellspawn are moving towards you.]]

"Scott, get out of there!"

"For once you don't have to tell me twice, John. Ugh, can't carry the powersuit. I'm leaving it behind. ...Gah, why is muscle so heavy?!"

"Pods Alpha and Bravo to Thunderbird One," Gordon patched in. "We'll be there in two minutes. Stay put."

"No time, there's another attack coming. I'll meet you halfway. And hurry up, Virgil's heavy!"

"Scotty, Scotty, can't you be concerned about his health?"

"After I'm out of this mess!"

One-and-a-half minutes later, Pod Alpha's headlights illuminated Scott, who quickly altered course towards them, still carrying Virgil. Behind him, the headlights also reflected off the alien eyes of a pack of six hellspawn.

"Wow," Alan observed from Pod Bravo, "those things look dangerous. And ugly."

"Yep, they do. You're carrying Scott." Gordon opened the hatch and shouted, "Put Virgil in here, I'll strap him in!"

Scott dumped Virgil in the back seat of Alpha. As Gordon strapped the latter in, the former climbed into Bravo. With all passengers secure, the pods turned around and left with all possible haste.

"International Rescue, this is Thunderbird Five. Colonel Casey wants to know whether to deploy containment teams or an airstrike."

"Airstrike," said Scott. "Definitely airstrike."

"Scott?" This fazed Gordon. "You're a bit trigger-happy...?"

"Try fighting those things and see how you feel." Scott glanced backward and paled. "Alan, speed up! They're gaining!"

The pods now moved with more haste than was possible.

"Those things are too fast," Alan thought out loud. "We can barely outrun them at full speed."

Fortunately, they didn't really have to try, because then Gordon saw them stop. "Scott, they've given up! They're turning around!"

"Keep going. We're still getting that airstrike." Scott shuddered. "Those things are freaky."

"No argument there..." said Alan. "Oh! Exit in thirty seconds."

"Colonel Casey, prep the airstrike," Scott ordered. "Fire as soon as we're clear. Bring down the whole building for all I care. I'm not taking any chances."

There were no further signs of pursuit, but that didn't reassure anyone. Almost before the pods were clear, the airstrike commenced. A barrage of missiles collapsed the building into a pile of rubble.

As Thunderbird Two collected the pods and departed to get medical attention for Virgil, Thunderbird Five reported that nothing was left alive under the rubble. This was a slightly premature, if understandable, conclusion; most of the alien creatures under the rubble were now dead, and the two survivors were (somewhat intentionally) best suited to evade Thunderbird Five's scans.

One was small, efficient, and only hatched from its egg after Five's attention departed. The other was even more incomprehensibly alien. Between them, they were uniquely well-suited to rebuild the hive by its bootstraps.