AN: I don't own Fallout or Halo. They belong to Bethesda and Bungie/Microsoft/343 Industries respectively.

Chapter One

UNSC Frigate Heavy Hitter, Slipstream space – unknown coordinates near Sol Star System. 0539 Hours, September 05, 2552 (Military Calendar)

The bridge was uncharacteristically quiet as Captain Jonathan McNeal stepped inside, smoothing a few wrinkles from his service uniform. He looked over the room, frowning at the lack of crew present, then made his way towards the command chair and eased himself down into it.

'Sasha, situation update, please,' McNeal said as he leaned back and shifted, trying to get comfortable in the well worn seat.

As he spoke, a nearby holotank hummed into life and the translucent image of a woman appeared, Sasha, the smart AI assigned to the Heavy Hitter. Like every other AI in the UNSC, she had a unique avatar.

McNeal had worked with one whose chosen image was reminiscent of a Viking warrior, whilst another had resembled a Marine in full combat gear complete with holstered pistol, but Sasha had settled on a simple design of a white jumper over dark trousers, and her personality matched it almost perfectly.

Many AIs had quirky personalities, a result of their advanced programming and sophistication, but not Sasha. Instead, she was quiet, even when interacting with the crew, and had a facial of bored disinterest to match.

'All systems operating normally, and we will be dropping back into normal space within thirty minutes, give or take five minutes,' Sasha said. 'Weapon safeties are engaged, MAC gun capacitors at zero charge.'

Sasha folded her arms across her chest, her usual stance when nothing of interest was happening.

'And the security personnel?' McNeal asked.

The Heavy Hitter was a Charon-class frigate, suited for supporting ground operations rather than ship-to-ship battles, and was often employed to move large numbers of Marines from planet to planet, of which there were currently two whole companies onboard, plus two platoons of ODSTs, and a single Spartan supersoldier, all them recovering from a recent battle that had seen their numbers badly mauled.

Neither of the Marine companies were made up of their original rosters, having absorbed soldiers from other units which had been mauled badly, and the ODSTs were more or less fully intact save for a few recent additions.

'Still in cryo,' Sasha said. 'I'll begin the thawing procedure when we transition to normal space.'

The AI blew an errant strand of hair from her face as the bridge doors slid open, revealing the first of the bridge crew.

More than a few were rubbing their arms, trying to warm them up after the freezing temperatures of cryo sleep, but they quickly sat down in front of their assigned workstations, McNeal saying a small help to each as they passed.

On navigation was Lieutenant Franks, a recent addition to the command crew after a medical discharge had robbed them of their previous navigation officer. He was usually quiet around the others but was slowly becoming more and more confident around them with each passing day. According to his file, the young lieutenant had never been in actual combat against the Covenant before and aside from simulations back at OCS, this was his first tour where he'd been on the bridge crew.

Next to Franks, and manning the weapons console, was Lieutenant Donovan. Like his neighbour, Donovan was new to the Heavy Hitter but had previously served on two other ships before arriving on the frigate. He was more open than Franks and quick to strike up conversations, and had already started up several budding friendships with some of the other officers.

The next station, communications, was staffed by Lieutenant Murphy. Unlike Donovan and Franks, he was the only officer who had served aboard the ship since it had first left Reach, the UNSC's primary shipbuilding yard, initially as its commanding officer, but after an incident involving two other naval officers, four Marines, and several thousand credits worth of damage to a bar, he had been forced to take a two-step demotion down from Commander to Lieutenant.

It was only due to a heartfelt plea that Murphy had been allowed to remain aboard the Heavy Hitter, even if it was as the ship's communications officer and XO. The experience had left him somewhat disgruntled and prone to verbally lashing out on bad days.

Lastly, on operations, was Lieutenant Tyler. Her records made note that this was her third tour of duty, and that she was hoping to go onto a fourth despite seeing dozens of planets glassed and thousands of fellow naval personnel die. She showed no signs of cracking or snapping. On the contrary, she was the most upbeat of the command crew but given the usually dour atmosphere that pervaded the bride, this wasn't very hard.

'Transition to normal space in five minutes, plus or minus two minutes,' Sasha announced.

'Very well,' McNeal said, strapping himself into his chair.

The other officers did the same, cinching them tight in anticipation.

'Returning to normal space in three, two, one,' Sasha said, blowing another errant strand of hair from her face as the ship dropped out of slipspace and decelerated sharply, throwing the bridge crew forward against their restraints.

As they did, the forward viewscreens seemed to snap on as thousands of stars appeared, replacing the dark and featureless void that was slipspace.

'Lieutenant Franks, plot a course to Earth,' McNeal ordered. 'Lieutenant Tyler, bring the reactor to fifty percent.'

'Aye, sir,' both officers said simultaneously, tapping various commands into their respective stations.

The ship rumbled and slowly titled as it moved, angling towards humanity's home planet.

'Course plotted,' Franks said, sounding happy as he finished typing in the ship's new route. 'ETA is thirty-two minutes, eight seconds.'

On the communications station, however, Murphy frowned as he tapped his own commands in, slapping the monitor after a few seconds.

'Sir, could you come here for a moment?' he said as he frown depend. 'I think there's something you'll need to see.'

McNeal raised an eyebrow as he looked at the man but stood and made his way over, peering at the screen in question when he reached Murphy.

'All right, Lieutenant. What am I looking at?'

Captain McNeal had never worked as a communications officer, instead having been assigned to operations. As a result, the screen Murphy was frowning at was a mystery.

'Nothing, sir,' Murphy said, waving his hand at the screen. 'Absolutely nothing.'

He tapped at the keyboard again but the image stayed the same.

'I'm not sure I follow,' McNeal said. 'Why did you call me over to look at nothing?'

'Because there's usually something on here, sir.' Murphy pointed at several flat lines. 'These represent the signals of every UNSC channel. The thicker the lie, the better the signal. But notice how they're all really thin?' he indicated each line in turn. 'It means we aren't receiving any signals at all, sir.'

'Could it be a problem with the equipment?' McNeal speculated, a frown of his own forming.

'No, sir. I triple checked it before we dropped back into normal space and again when I didn't see any signals.' The lieutenant turned to face McNeal. 'There's nothing wrong with our equipment. It's working perfectly fine.'

'So why aren't we getting anything?'

'I don't know, sir.' Murphy turned back to his station and started tapping at the keyboard again. In response, the screen went blank and then came on again as he took it through yet another systems check. 'But what I do know is that we're green across the board.'

'Keep checking, lieutenant,' McNeal said as he stepped away and returned to his chair, sitting back down as the Heavy Hitter drew closer to Earth.

UNSC Frigate Heavy Hitter, en route to Earth. 0713 Hours, September 05, 2552 (Military Calendar)

McNeal anxiously twiddled his thumbs as the frigate edged ever nearer to Earth, a trait shared by the rest of the crew,

For the past half an hour, Murphy had tried and tried to find any kind of signal, putting the communications system through dozens of self diagnostics. Each time it had come back as working normally, infuriating the lieutenant and worrying the others.

The feeling had only grown worse when the ship's radar had failed to pick up the presence of any UNSC vessel, mobile or otherwise. To have one piece of faulty equipment was unheard of. To have two was almost impossible.

It made McNeal very nervous.

'Lieutenant Donovan, arm the MAC gun and remove Archer missile safeties,' he ordered. 'I want them ready to fire on a moment's notice.

'Aye, sir,' Donovan replied as he entered the commands to bring every weapon the Heavy had online and ready to fire. 'MAC gun charging, Archer missile safeties removed.'

'Lieutenant Franks, plot a slingshot orbit around the planet,' McNeal added, strapping himself in. 'Lieutenant Tyler, bring the reactor up to ninety percent.

'Slingshot orbit plotted,' Franks announced.

'Reactors responding,' Tyler said. 'Coming up to ninety percent now.'

The frigate rumbled and accelerated, almost heading straight for the planet before turning away and presenting its starboard side to the surface.

'Captain, I'm picking up an anomalous radiation reading from the planet,' Sasha said, hands on her hips, her stance for when things had gotten interesting. 'It's more than ten times the normal background radiation count and that's not all.'

Before she could elaborate any further, a shout went up from navigation as the frigate flew around the planet.

'Sir, got a new contact,' Franks said. 'Unknown classification.'

'Where?' McNeal asked.

'Contact is thirty-eight thousand kilometres distant, bearing zero-three-four.'

The navigation officer wiped a bead of sweat from his brow as he highlighted the unknown on the forward viewscreen, zooming in so the bridge could see.

'Sir, it appears to be in a geosynchronous orbit over the eastern coast of America.'

'Is it Covenant?' McNeal asked.

'Negative, Captain,' Sasha said as she overlaid the unknown craft's profile over those of every known Covenant ship stored in her memory, their designs bristling with flowing lines and oddly predatory styling. On the contrary, the ship hanging before them looked nothing like, having more in common with flying saucers from cheesy science fiction movies from Earth's past. 'The craft fits no known profile, human or Covenant.'

'Jesus, a whole new alien species,' Murphy muttered. 'Just when I though life couldn't get any better.'

'Has it tried to communicate?' McNeal asked, ignoring his communications officer's sarcasm.

'Negative, sir. All channels clear,' Murphy said. 'Shall I try to message them?'

'Yes, we'll give them three minutes to-' McNeal began to say but was cut off by Franks.

'Sir, contact is moving,' he said.

'To where?'

'Nowhere, sir. It's rotating.'

Franks pulled the image of the ship back so the whole crew could see what he meant.

Originally, the vessel had been orbiting with its flat side parallel to the Earth, presenting a wide target for the Heavy's radar to bounce off and give them an image.

Now it had shifted to present the thin edge to the frigate, and from this new angle McNeal could see a smaller disk sat beneath the main body, and beneath that was an even smaller lump.

'Sasha, zoom and enhance at the very bottom of the craft,' he ordered. 'There's something there.'

'Aye, sir. Zooming and enhancing,' Sasha said as she squinted, manipulating the image to focus on the smaller disk and the anomalous lump it carried.

The image jumped and blurred as it zoomed in before sharpening up again as Sasha adjusted the focus, the end result grainy but clear enough for everyone present to see a distinctive shape.

'Is that a cannon?' McNeal thought aloud.

'Possibly,' Sasha said.

'Energy spike!' Lieutenant Franks yelled. 'Detecting high levels from the contact.'

He tapped furiously at his keyboard, reverting the image of the UFO back to what it had once been.

'Can you specify which region?' McNeal asked.

By now, the frigate had closed the distance between itself and the unknown ship.

'Energy spike located at the bottom of the ship,' Franks said, focusing on his screen. 'More specifically, their cannon.'

'Do they have a lock on us?' McNeal asked as he looked between his navigation officer and the forward viewscreen.

'Aye, sir. Contact has acquired target lock,' Murphy announced.

'Weapon status?'

'MAC gun still hot, all Archer missiles primed and ready for launch,' Donovan said.

'Range to ship?'

McNeal and the others either tightened their restraints or slipped them back on.

'Unknown ship now five thousand kilometres,' Franks said.

'All engines stop, shift to station keeping,' McNeal ordered. 'Sasha, I was us pointed at that thing. Donovan, arm Archer pods A through D and get me a firing solution.' He clicked the intercom on. 'All hands, battle stations.'

'Aye, aye, sir,' the bridge crew responded, jumping to their tasks as sweat beaded on the foreheads, the bridge lights darkening to a red hue.

'Archer pods A through D armed,' Donovan said. 'Firing solution acquired. MAC gun still charged and ready.'

There were a series of small rumblings as the Heavy Hitter's manoeuvring thrusters repositioned the ship to keep it pointed directly at the UFO.

'Ship in position,' Sasha said, hands on her hips as she stared directly at the viewscreen. 'We've got them in our sights.'

'Energy levels on contact have spiked again,' Franks yelled. 'Now triple previous levels.

He adjusted one of the forward viewscreens to show a magnified image of the UFO's cannon, now glowing green along several lines that terminated at a single point.

'Transfer emergency thruster control to Sasha. If that is a weapon, I want to be able to dodge it if it fires,' McNeal said.

'Transferring thruster control to Sasha. Aye, sir,' Franks muttered, watching his screen intently for any change.

'Not that we'll know exactly when that thing will fire,' Sasha said. 'Provided it is a weapon.'

'Call it a hunch,' McNeal countered.

'Very well, sir,' the AI said, cupping her chin with one hand.

On screen, the image of the ship's cannon grew brighter as what looked like electricity danced across its surface until, without warning, the light exploded and a thin green ray erupted from the tip and sped towards the frigate.

As it did, Sasha detonated the emergency thrusters and blasted the Heavy Hitter to port away from the ray in hope of avoiding the glowing lance of light.

Unfortunately, it didn't work and the beam sliced through the starboard engines, a number of alarms blaring into life as the ship shook from secondary explosions and started a slow spin.

'Status!' McNeal yelled, gripping the arms of his chair tightly.

'Starboard engine has been hit but I can't get a clear pictures as to how badly,' Tyler shouted, fighting against the alarms. 'There's a hull breach in the engineering section and a leak in the starboard fuel tanks. Sealing damaged sections and pumping what I can to the port and reserve tanks.'

'Weapon status?'

'MAC still fully charged and Archer pods A through D still locked on,' Donovan said. 'But I can't fire until we're straight and level.'

'Acknowledged.' McNeal turned to navigation. 'Lieutenant Franks, I want us pointed at that son of a bitch and kept there. If he wants a fight, we'll give him one.'

'Aye, sir,' Franks said. 'Countering our spin.'

Onscreen, the stars that had been swirling around slowed and then stopped as the frigate came to a halt before being replaced by the enemy target.

'Lieutenant Donovan, are we locked on?' McNeal asked.

'Aye, aye, sir,' he answered. 'Firing solution ready.'

'Then fire,' McNeal ordered. 'Blow it out of the stars.'

'Pods A through D firing!'

There was a series of small thumps as over 120 missiles left the wounded ship and accelerated towards the alien ship which made no attempt to avoid them, or even shoot them out of the sky.

Instead it just sat there as they closed the gap and impacted across its hull, fire covering nearly every inch of it and for a brief second, there was a silvery film wherever the missiles hit it was gone just as quickly as it had appeared, allowing the follow up explosives to tear up the alien hull.

'MAC firing,' Donovan said as every light on the bridge dimmed a mere second before a white hot streak of metal flew from the prow of the frigate and slammed into the already damaged hull of the enemy.

Unlike the missiles, there was no silvery film as the six-hundred ton slug impacted, or as it careered through the metal plating and tore out of the opposite end. Internal explosions blossomed out of the new hole, ejecting fresh pieces of debris into space, but the craft refused to explode.

'Arm pods E through H, identical firing solution,' McNeal ordered calmly.

'Aye, sir. Arming pods E through H, identical firing solution,' Donovan said as he quickly typed in the necessary commands, finger poised over the execute button.

'Fire,' McNeal said softly.

Donovan nodded and pressed the button, sending another salvo of 120 missiles on their short journey.

They left the Heavy Hitter and flew through the vacuum of space to their intended target, throwing more fire and shrapnel out upon impacting and detonating.

Now the alien vessel finally detonated, exploding into three distinct pieces with countless smaller parts falling off and drifting towards the planet below, caught in its gravity well.

The bridge crew watched as they slowly burned during re-entry, leaving behind little wisps of smoke, before relaxing slightly.

'All hands, secure from battle stations,' McNeal said into the intercom as the last piece vanished from sight. He switched it off and gazed at the planet below, a frown creasing his features. 'Sasha, how sure are you that that's the Earth?'

'Fairly certain, Captain,' she said, face scrunched up in concentration. 'All of the other planets are present, the constellations match, and the energy output of the sun is the same. The only things that aren't the same is the background radiation count and that fact that the Earth and Moon are marginally closer to each other than they should be.

'We are, without a shadow of a doubt, at Earth.'

She folded her arms as the bridge fell into a stunned silence.

'We-We can't be,' Tyler whispered. 'There must be come mistake.'

'There isn't, Lieutenant,' Sasha said. 'That is Earth.'

McNeal unclipped himself and stood, walking to the forward viewscreens.

'If it is, what the hell happened?' he asked. 'And when?'

'Unknown.'

'Then we'd better find out.' McNeal span around and faced the bridge crew. 'I want an expedition organised to go planetside. They're to find out whatever they can about what happened down there, and when.'

'Could they also find a heavy manufacturing plant as well?' Tyler asked, reading something from her screen. 'That beam cut through the starboard engine and caused some kind of electrical feedback, which in turn fried a number of components and damaged them, the slipspace drive included.

'Can we fix it ourselves?' McNeal asked as he sat down in his chair.

'No, sir. The drive requires parts we either don't have or can't make.' She span in her chair to face the captain. 'Mostly it's the circuits which control the drive but there are a few other components which need to be replaced. Until then, we can't jump to slipspace.'

'Not that there's anywhere to go,' Murphy said. 'I can't pick up any UNSC signals. HIGHCOM, FLEETCOM, SATCOM. Everything is missing, which means there is nothing broadcasting.'

'One problem at a time, lieutenant,' McNeal said. 'First we find out what down there, then we find out what happened to us.' He rubbed his face and let out a small breath. 'Lieutenant Franks, put us in orbit over the eastern seaboard. We're going in.'