This story is set in the original Thunderbirds TV-verse (1965), and in the original Captain Scarlet and the Mysterons universe (1967, although I am admittedly less strict about the Captain Scarlet universe and apologise if any New Captain Scarlet references slip in - I will try hard to control myself.)

As this is a crossover, and as I like to think that Thunderbirds and Captain Scarlet exist in the same world and time, this story uses the 2060s timeline.

As ever, all thanks go to the Andersons for blessing us with such outstanding entertainment for the last 50 years. (Can you believe it? 50 years!)

zero point

prologue

'Eyes open Gordon, we're about to break through.'

'Got it.' Gordon punched a keypad and glanced up at the overhead monitor. 'Externals active.'

'Acknowledged.' Virgil geared the Mole down and prepared to break through into the sub-basement ahead. The sprawling complex of Faulkner Labs had collapsed on itself during a freak earth tremor – a simple enough rescue for a well-equipped response team, but IR had been called in when the rupturing of isotope casings stored in the facility had made entering the building too hazardous for local authorities to attempt.

It seemed these days that International Rescue was increasingly about containment – six months earlier a rescue at a university in Chile was compromised after its entire store of experimental viruses was released during an earthquake, and a few months after that IR had been called in to recover one of Virgin Galactic's experimental hyperdrive ships as it threatened to dump its core into the atmosphere. Virgil was all for the advancement of technology and the development of new sources of energy, but why the hell couldn't these people ever get their procedures under control?

The Mole lurched suddenly and the view through the forward screen changed, the rock through which they'd been tunnelling falling away to reveal a splinter of light and the laboratory they'd been aiming for.

'We're in.' Virgil powered the systems down and unbuckled his harness, grimacing as Gordon dropped a hazard suit onto the deck at his feet. Virgil hated wearing the suits. Hated the constriction of his movements, hated the breathing and rebreathing of filtered air. But if there was uncontained radiation in this basement then they had to take precautions, and that included decontaminating themselves – and all their equipment – afterwards. He rubbed a hand wearily across his face at the thought. 'Better get us a radiation reading.'

Gordon fed the scan through to the main console so Virgil could see it for himself, and then routed the readout to Scott at Mobile Control for confirmation. 'Weird,' he said, sitting back in his seat so he could watch Virgil's face. 'There's nothing out there except background. It's clear.'

Virgil turned to look incredulously at his younger brother. 'Then why the hell are we here?'

'You're sure about that?' Scott studied the Mole feed intently before turning his head to stare at the dark-suited man hovering nervously beside him.

'No, I'm not.' Virgil's voice sounded weary in Scott's headset. 'But you've got the same readings we have. Unless we've misinterpreted it or the sensors are malfunctioning, the area is clear.'

'Understood.' Scott continued staring at the gentleman beside him. 'I've got the Faulkner CEO here. Stand by.' He cut the connection and swivelled in his seat.

Martin Brooks was by nature a nervous man, but today his anxieties had reached critical levels. He shifted uncomfortably on his feet, wilting beneath the onslaught of the cool blue eyes that fixed themselves unwaveringly on him. 'I can explain.'

'Explain what?' Scott removed his headset and rose to his full height, which was considerably taller than Faulkner Labs' sweating CEO. 'Either there is hazardous material in that building, or there isn't. And if there isn't, and if we've been called out to a situation that the local services could have managed, then your corporation will be liable for all costs incurred.'

Brooks removed a handkerchief from his pocket and wiped at his face. 'More than happy to pay for the costs, no matter the outcome. But there is hazardous material in that basement, and one of my scientists is unaccounted for. Please.' He fumbled the handkerchief back into his pocket. 'This is a lot worse than it looks.'

Scott's gaze didn't waver. 'How much worse?'

'Interesting.' Gordon closed the zip on his hazard suit and slumped back into his seat as the radio silence continued. 'What do you think's going on?'

'No frickin' idea.' Virgil jammed his hands into the gloves of his suit and methodically connected the seals.

Gordon turned his attention to the helmet in his lap, licked his thumb and swiped at a smudge on the faceplate, and then lowered the helmet carefully to the floor. He leaned back over his console and toggled randomly through the external readings. Oxygen, temperature, contaminants –

'Mole from Mobile Control.' Scott's voice came unevenly through the speaker, the transmission splintered by thirty metres of solid rock.

Virgil shifted in his seat and turned towards the comms. 'Reading you.'

'CEO says there should be only one man in the sub-basement, a William Masters, and he was working on some kind of perpetual energy device when the building came down.'

Virgil turned to Gordon and frowned. 'Life signs?' he mouthed silently. Gordon shook his head in the negative and Virgil returned his attention back to the comms. 'Can you confirm no radiation?' he said into the microphone.

'No radiation,' Scott confirmed. 'But the device apparently has other effects, so keep those hazard suits on.'

"Um...' Gordon came to lean over Virgil's shoulder. 'Mobile Control, what do you mean by 'other effects'?'

'Unclear.' A burst of static cut through Scott's voice. 'The CEO thinks the device may have been the cause of the earth tremor, so your first job is to cut the power on that thing before it brings the rest of the city down.'

Virgil rubbed distractedly at his mouth. 'FAB,' he finally said, killing the connection and looking dubiously at his brother.

Gordon shook his head incredulously. 'What the hell did he mean by 'other effects'? And what could be in there that's dangerous enough to bring a city down? He's kidding, right?'

'You know as well as I do that when Scott is sitting at that console he doesn't have a single funny bone in his body.' Virgil pulled the helmet of his suit into place and activated the seals. 'Ready?'

To Gordon, it always felt like walking in space. The cavernous dark of the underground held the same disconnect from reality. The same sense that you never really knew which way was up.

He exited the Mole ahead of Virgil, his booted feet treading unsteadily over broken stone, and aimed his torch back along the tunnel through which the Mole had just bored. Reassured that the way back out was clear, Gordon turned his attention to the fractured wall ahead of him and the shard of yellow light that splintered past the nose of the Mole and collected in a pale pool on the ground at his feet.

'Can you hear that?' Gordon aimed the torch towards the source of the light.

'Hear what?' Virgil dropped down from the Mole and landed awkwardly in the field of broken rock. 'Shit. No. What can you hear?'

'That.' Gordon stepped closer to the rent in the wall and leaned his face towards the opening. 'A humming sound.' He cocked his head, listening. 'Hear it?'

'Must be the power source.' Virgil came up behind him and nodded confirmation as the sound became more audible. 'C'mon.' He prodded Gordon towards the opening.

Gordon clamped his hands against the broken edges of the wall and hauled himself through to the laboratory, stumbling over pieces of plaster and tile as his brother clambered through the opening behind him. He kicked a clear space in the debris and turned to survey the area.

'Holy crap…' Gordon breathed as the source of the light became visible.

'What the hell is it?' Virgil's voice echoed through the helmet comms.

'And how the hell did it do that?' Gordon directed Virgil's attention down towards the tiled floor.

'Mobile Control to Mole team.' Scott's voice cut abruptly through the open channel, making them both jump. 'Show me what you're looking at.'

Gordon shook his head silently.

'Scott…' Virgil began.

'Give me a visual,' Scott ordered.

Gordon raised a hand to his helmet cam. 'Mobile Control,' he cautioned. 'We've located Masters, and it isn't pretty.'

'Understood.'

Gordon glanced at Virgil as he activated the camera. 'Mobile Control, are you receiving?'

'Affirmative.' Static crackled through the connection. 'Stand by.'

Gordon kept his helmet cam pointed down at Masters, but aimed his eyeballs back towards the source of the mysterious light. 'What do you think it is?' he said to Virgil.

'I don't know.' Virgil stepped away from Gordon's side and began to pick his way along the wall of the lab. 'Some kind of energy generator, they said.'

'Careful.' Gordon's eyes followed Virgil's movements. 'Don't get too close to it. You've seen what it can do.'

Virgil stopped to stare at the swirling sphere of energy that occupied the centre of the room. 'Don't worry,' he responded distractedly, fighting the urge to reach out and push his fingers through the sphere and into the bubble of light beyond. His eyes fell to where Masters lay, half in and half out of the bubble, his body cauterised neatly in two. Virgil curled his fingers carefully into his palm.

'Mobile Control to Mole team.' Scott's voice echoed loudly in their ears, made them jump again. 'At this point your priority is to shut off power to the device.'

'No shit, Sherlock,' Gordon muttered beneath his breath.

'I didn't copy that. Please repeat.'

'Repeating, Mobile Control. Can you advise shut-off procedure.' Gordon turned his head to follow Virgil as he recommenced his trek to the far side of the room. Seen through the swirling mass of yellow light Virgil appeared pale and distorted, a shimmering ghost with uncertain edges.

'Stand by.'

'Standing by,' Gordon acknowledged. He pivoted in position, looked at the sphere, the walls, the two neat pieces of Masters where they lay on the floor. 'Virg,' he called out. 'I think it's changing.'

Across the room Virgil stopped and turned to look at his brother through the shimmering field of light.

'The colour.' Gordon indicated the bubble with a nod of his head. 'It's changing.'

Virgil stared into the light.

'And the noise is getting louder.' Gordon could feel sweat forming on his brow as he fought down the sudden urge to get out of there as fast as he could.

Virgil shook his head, the movement barely perceptible through the shifting dome of light. 'I don't think so. I think – '

'Mobile Control to Mole team.'

Virgil closed his mouth at the interruption.

'Shut-off instructions as follows.'

'Reading you,' Virgil acknowledged. 'I'm standing at what looks like the main console now.' He glanced down at the console, at the switch marked 'mains power,' and hoped it would be that easy.

'There should be a monitor displaying power inputs and outputs,' Scott's voice filtered into his helmet, 'and a graph logging something called neutron initiation.'

Nope. It wasn't going to be that easy. 'I see it.'

'We need you to take that down to zero, but slowly. The CEO advises a minimum of eight minutes to shut-down, depending on the dampening effect.'

Crap. 'Get over here,' Virgil called to Gordon. 'I need you to time this.'

Gordon didn't move from his position. 'That thing is definitely getting bigger.' He gestured towards the body of Masters. 'When we got here, most of his legs were outside the bubble. And it seems to have swallowed more of the floor.'

Virgil squinted towards the two feet that protruded from the energy mass. 'Shit,' he cursed beneath his breath, then said out loud, 'Mobile Control, we may have a situation.'

'I heard,' Scott said, his voice sounding small and far away. 'Continue the shut-down sequence. Gordon, show me what's happening.'

'This thing is growing by the second.' Gordon pivoted on his heels and performed a slow pan of the lab. 'I don't think we have enough time to shut it down.'

'There's time,' Scott replied, his voice tight beneath the rising static.

Gordon licked at the salt that had settled on his lips. 'Scott – '

'There's time.'

'Are you seeing what I'm seeing?' Gordon aimed the camera squarely at the energy bubble, at the boiling, swirling mass of yellow light. 'This thing is changing.'

'He's right, Scott,' Virgil cut into the conversation. 'I've commenced the shut-down procedure, but the monitor indicates the neutron energy is still peaking.'

'Give me a visual on the console, Virgil.'

Virgil dutifully activated his helmet camera, waiting in silence as Scott and the Faulkner CEO discussed their options thirty metres above them. He winced as the background hum increased in pitch and penetrated uncomfortably into his brain.

'Did you feel that?' Gordon said from the other side of the bubble, his voice muffled by the increasing hum. 'The floor just moved.'

Virgil felt it, saw a trickle of plaster fall from the ceiling and disappear sparking into the sphere. If this thing caused another quake… 'Shut up and time me.'

'Ninety seconds down,' Gordon replied with a grim efficiency that indicated he hadn't taken his mind off the process for a second. 'It's getting brighter.'

The floor shuddered again, and tiles splintered free from the walls around them.

'Fuck.' Sweat dripped stinging into Virgil's eyes and he blinked, unable to wipe his face through the bulky contamination suit. His vision blurred as the light changed, the yellow burning across the spectrum to a sick and violent green. He turned his attention back to the console, to the neutron indicator peaking past maximum. 'Time,' he snapped at his brother as he reduced the power one more level and watched incredulous as the neutron indicator moved into the red.

'One-eighty.' Gordon's voice came out of the burning light as he continued his countdown. 'It's getting bigger,' he shouted over the increasing hum.

Virgil glanced over his shoulder, the edge of the bubble less than a metre away from him. The readings on the console showed that the external power was reducing, yet the sphere continued growing before his eyes, expanding ever-outwards in visibly perceptible pulses. The body of Masters was now fully engulfed, and laboratory equipment was disappearing millimetre by millimetre into the burning light as he watched.

'It's drawing on another energy source,' Virgil shouted over the comms. 'I think it's self-perpetuating. I can't shut it off!'

'We need to get out of here!' Gordon bellowed as the comms in his suit failed, the hum of the sphere drowning out all sound the same way that the light now drowned out his vision.

Scott's world was turning to shit. All he could see on the screen was green. He could barely hear Brooks' voice as he intoned instructions beside him, the words tumbling out of the CEO's mouth as he blabbered about neutron energy and quantum electrodynamics and –

'Gordon, listen to me,' Scott barked into the mic, but the comms were down. Dead. Not even static burned the speakers and Scott was left with Gordon's last frantic words echoing in his ears… We need to get out of here…

Scott lashed out a hand, grabbed hold of Brooks by the shirt and pulled him up to his level. 'What is this thing?' He could barely restrain his anger as his fingers twisted into the starched linen and he felt the fabric give way in his hand. 'Tell me how to shut it off!'

'You can't.' Brooks dangled helpless in Scott's grip, his voice now faint and trembling. 'Equilibrium has failed. Get your men out of there before it's too late.'

Virgil backed up against the console as the perimeter of the sphere expanded inexorably towards him, an oily, gelatinous bubble poised electric inches from his face.

'Gordon,' he said into the dead comms, his words useless against the increasing noise as the sphere continued its relentless advance. He could no longer see his brother, the burning light drowning out all colour, all sound, all evidence of the room around him. The floor shifted beneath his feet, the console vibrating at his back, and he was vaguely aware of dust falling from the ceiling and drifting down the visor of his helmet. 'Gordon,' Virgil said again, hoping that his brother wasn't waiting for him on the other side of the light – or worse, was trying to fight his way around the sphere to get to him.

Shit.

With the certainty that came from brothers being brothers, Virgil began to carefully inch his way around the sphere, his limbs restricted by the bulky suit so that he could barely move, could hardly breathe, couldn't see through the moisture that was building up inside his faceplate. Sweat slicked his brow, trickled into his eyes and hovered in tremulous, annoying drops on the tips of his lashes. He blinked ineffectually, eyes burning from the salt and the light, every atom of his body alert to the danger that loomed so close to his face. The surface of the sphere was alive with static, tendrils that he could see on the afterburn of his retinas, and feel, stinging him, through the thick skin of his suit. And the noise… the noise was overwhelming, penetrating his brain like thin, hot knives, and pulsing and vibrating the molecules of his body the same way that it was vibrating the atoms of the air around him.

There was pulse, a tangible sensation that made his flesh crawl as electricity sparked from the sphere and penetrated his suit, tracked stinging across the moist surface of his skin, discharged itself crackling through the roots of his hair. A wall of sound erupted out of the light and shattered the walls around him, tilted the floor and knocked him from his feet, sent him tumbling helpless into the shimmering, pulsing sphere. Virgil only had time to close his eyes as he passed through the membrane of light, although it did him no good, the light rushing into him and filling him with fire. He felt a scream coil in the back of his throat, but the light stole the sound from his mouth, sucked the air from his lungs and evaporated the moisture from his tongue. Electricity forked green across his retinas and then all was darkness. And silence. And the screaming inside him ceased.