Azian's body hung limp in Eli's arms. He was so shocked he couldn't summon the grief to cry. This couldn't be happening, could it? The day had passed like a flash of lightning, events whirling by ever since Gordon Freeman had disappeared into the test chamber. That very morning Eli had woken up with Azian at his side, now he had found her sprawled in the corner of some warehouse, her skin mottled with puffy blemishes where hornets from the burly alien's weapon had made their marks. Azian's eyes were halfway open, staring at the warehouse wall.

Eli slumped against a nearby crate. Now the grief came. Bringing his knees to his chest and curling into a ball, he wept not with shaking sobs but the resigned whimpering of a man who still couldn't quite be sure he hadn't stepped into some nightmare. Things would make much more sense if he were to wake up then and there, snapping back to a reality where there were no aliens, crystals of exotic matter, or grey-skinned men with briefcases.

Eli closed his eyes until the waves of despair had passed, at least for the moment. He looked with bloodshot eyes at the body of his wife, crumpled against the wall. Assuming the pace of circumstances would at some point slow down and life would return to its usual tempo, there would be time to mourn Azian later.

He drew himself up to his full height. He didn't want to leave Azian the way she was, the way the creatures had left her, it was undignified, but he had little choice. He slung his rucksack over his shoulder. Before searching the warehouses carefully and coming upon his dead wife, he had cast about the dormitories below ground, frustrated that neither his family nor anyone else was to be found there. He had found a rucksack in his dormitory, and filled it full of precious things, including a photo of him, Azian and Alyx when she was still a baby. Speaking of precious things, there was one more thing he had to do before leaving Azian. He reached around his wife's neck, already lacking the warmth of life, and undid her necklace. He didn't know the value of the thing, but he did know what Azian had once told him: that the box-like jewel worn around her neck was passed on from mother to daughter. It belonged to Alyx now.

But there was the question. Where was Alyx? She hadn't died, it seemed, next to her mother. So what had happened? Had she escaped or been abducted?

After the sight of his wife's dead corpse, all the hope seemed to have drained from Eli. Though there was nothing he wanted to see less, he wouldn't have been shocked at all to find his daughter's corpse lying somewhere. But nonetheless something kept him going, perhaps the tiny, flickering flame of a hope that Alyx might just be alive. If he found her dead, he might just walk into the fire of some hostile aliens, if any still remained. There would be no other reason for him to survive the crisis at Black Mesa. He put the little box necklace safely into a pocket of his bag, laid a final, mournful hand on Azian's shoulder, then left.

After leaving the dormitories he had passed up the nearby evacuation stairwell, but, frustrated at seeing the passage to the surface blocked, he had descended and sought out another means of getting to the surface. From there he had made his way to the warehouse sector.

The day was growing darker and the desert heat lessening. Eli wandered inside and around the storage sector like a man in a dream, recklessly indifferent should he come across more alien creatures. After a few minutes he came to the realisation that there were no longer any flashing portals sending in more warlike aliens. The only aliens Eli could see were the familiar corpses strewn over the red gravel.

Certain that his daughter was nowhere to be found in the storage sector, he started to ruminate. If his daughter was alive, and had left the warehouse where he had found Azian, where would she have gone next? If she had come across a group of Black Mesa employees like himself, they might have taken her to the nearest town. Eli had a vague impression as to what direction that might be, and started to head that way.

After much walking, he found himself at the old quarry, a pit that had existed since before the subterranean facility of Black Mesa had been excavated and opened. Eli thought he could hear a heavy scraping sound, almost a rhythmic pounding, and would have craned his neck over the quarry's edge to inspect the source of the noise, had he not spotted movement from the far side of the pit. It was undoubtedly humans he could see. They had neither the bulk of the larger creatures, the creeping of the smaller, collared ones, and they did not shamble like headcrab zombies. They were too far away for him to make them out individually, but from their dark and cumbersome apparel, he would have guessed they were facility security guards. They were headed in his direction. He could ask them if they had seen Alyx.

Eli stumbled towards them, heedless of the pounding sound which was growing louder. Soon his suspicions were confirmed. Most of the figures were security guards, bedecked in armour vests and helmets, though another seemed to be wearing the lab coat of a science team member.

Then, he saw the shape of someone smaller. His heart leapt. If the little form turned out to be anyone other than Alyx he felt he would die of disappointment.

But he wasn't wrong. Alyx's face lit up when she saw her father. Pushing passed her companions, she ran to Eli and father and daughter were finally reunited. Both wept openly.

Eli and Alyx had been undergoing similar emotions: The desperate hope that they would see each other again, despite how unlikely it was that that would come to pass. Both of them had seen so much death that day, the sight of a corpse becoming something commonplace. The prospect that the two of them would have survived the catastrophe had seemed near impossible, yet here it had come to pass. Alyx spoke the obvious, but something needed to be said:

'Dad, I thought you were dead.'

'I know sweetie. I'm here now.'

'I was with Mom. Then I ended up here somehow.'

At the reference to Azian, Eli wanted to break down into tears completely, but the day wasn't over. It wasn't certain that they were out of danger.

'Baby, your Mom is…'

'She…she's gone.'

Alyx realised this truth for the first time just as she said it. She hadn't seen her mother die, but somehow she knew it had to be the case. There was no reason to avoid the subject. The day of the Resonance Cascade had changed them both, making them frank about morbid subjects.

'Here', said Eli. 'This is from her. She would have wanted you to have it.'

Eli removed Azian's box necklace from a pocket and deftly strung it around his daughter's neck. Alyx's looked down and touched the little ornament, tears brimming in her eyes.

The small group of Black Mesa personnel surrounding them watched in silence, each of them feeling a mixture of elation that the Vances had been reunited, as well as a general sense of grief for everyone who had died in the facility below.

All the while the group had ignored the scraping and pounding that seemed to be coming from the pit of the quarry. Perhaps they had grown used to the sound and it had become part of the ambience, but a few moments after it had stopped, the silence became quite conspicuous.

In the stillness, several elongated shadows stretched across the desert dust on which they stood, one of them blocking the low, orange sun from view. Everyone seemed to glance in the direction of the quarry at once. Looming mutely over its edge were three giant aliens of a sort they hadn't seen before. Green, segmented bodies stretched up and out of the pit, supporting heads which ended in blade-like points. Two appendages hung limp on either side of the head. Once they had drawn themselves up to their full height, they did not move.

The group of humans stood frozen, clearly expecting the creatures to attack or make some sort of movement, but they hung there, erect and silent, as if waiting for something.

'Oh my God.'

That was it. It was the lab-coated scientist who had let out the exclamation, and each of the three massive heads twitched in his direction, then one of the bladed heads sailed through the air with a speed which belied its massive size. In a moment, the scientist was knocked to the ground as a gargantuan head bulldozed into him, scraping him along the dusty earth. The appendages gripped him, wrapping themselves around his torso. At first, he was winded, but as the head rose into the air, carrying him with it, he became aware of what was happening and let out a scream that would wake the dead. Then, he and the tentacle disappeared down into the excavated pit and out of sight, the scientist's fearful howl growing distant.

By now everyone in the group was shouting with fear and scraping the dirt with their shoes, trying to scramble away from the edge of the quarry pit. This was all the compulsion the tentacle creatures needed. The remaining two rose further out of the pit, craning their segmented bodies forward to intercept the humans. Hearing the sound of several targets, one of the creatures moved its long body in a broad, sweeping motion, catching several of the guards, knocking them to their feet and bunching their writhing bodies together.

Eli saw what the alien was trying to do and ducked to the dusty ground, pushing Alyx down as he did so. The tentacle glided over both of them. The guards, however, were not so lucky. They were all clustered together, and their thrashing and scrambling to get to their feet did nothing to lessen the veracity of the tentacle creature's attack.

Somewhere in the back of his mind Eli realised that the monsters were reacting to sound rather than sight, hence their stillness a moment before when nobody had made a noise.

The second alien was now dragging the remaining guards over the quarry's edge while the third hung eerily in the empty space, its head cocked, listening.

By now, Alyx's surprise had turned to abject fear, and the little girl let out an involuntary wail.

'Quiet baby', hissed Eli. 'Quiet.'

His urging was too late. The final tentacle's head was already moving languidly through the air towards them, its green body craning over the rim of the quarry. Despite its slowness, Eli and Alyx didn't seem to have enough time to clamber to their feet and move away from the edge. The monster descended towards the sound of Alyx's whimpering. The little girl was not big enough for both of the creature's appendages to grasp her, but one of them wrapped itself around her leg and began to lift her off the ground, causing her to bawl even louder. Eli clasped his daughter's torso with all his might. He would not let this accursed day take what remained of his family. He and Alyx were going to survive.

Then, despite the strength of the beast, and because it was using only one of its grasping limbs instead of two, Alyx's leg began to slip from its clutches and she tumbled back onto her father. Eli held her little body close and the two of them darted backwards, though the tentacle must still have been picking up the vibrations their bodies made in the dust, because it pursued them.

They crawled backwards frantically, and just as the bladed head was about to reach them, it stopped. The monster had reached its fullest extent and could stretch no further. It pounded the dust with its pointed head angrily, then began to recede. Alyx and Eli, safe at last, both lay back on the ground, panting.

The father and daughter had been making their way across the New Mexico desert for close to two hours now. The sun, now a dark orange hue, was dipping into the horizon. The two of them had talked little. The day had taken so much out of both of them.

At long last Eli and Alyx started to grow closer to the little town of Encino. They observed the corpse of a gargantuan alien sprawled in the dust and riddled with innumerable bullet holes, its armour torn from its body and dried green body fluids crusting the ground around it. The two of them regarded the creature as they passed it with tired eyes. The military had certainly done their work. At least now there were no sounds of gunfire or unrest of any kind. That suggested peace had descended.

Soon, the two of them approached a wide, dusty road which stretched across the flat desert landscape and in a moment the low buildings of Encino grew closer. A great many human figures became visible, crowding the streets of the little town. It seemed nearly all of them were either members of the science team, civilians, or security guards. These people were flanked by soldiers holding MP5s. Apparently, the soldiers who had originally been sent in to silence the employees of the nearby facility for good had been given orders to work with the scientists once the struggle against the aliens had become too much for them.

That's how it should have been from the beginning, thought Eli. The military should have helped with the evacuation and focused their fire on the alien monsters instead of taking the cavalier option of trying to cover the whole thing up. They had bitten off more than they could chew.

People in security gear and besmirched lab coats, like Eli's, crowded the streets. Had there not been an ambience of apprehension, the atmosphere of Encino would have been quite pleasant. The Vances had passed through the place just once when they had first moved to Black Mesa. Its most recognisable landmark was an attractive and modern-looking bridge which loomed over the town in the distance, connecting a couple of remote and large ridges to one another.

Holding his daughter's hand, Eli drew closer to the throng. Nobody, either soldier or otherwise, seemed to pay them any attention. Perhaps the people here were used to evacuees joining them constantly from the ruin of Black Mesa. Eli accosted one of the soldiers, though he still felt some animosity toward the military for what they had done to his colleagues.

'Excuse me', he said. 'We just got here. What's going on?'

The soldier turned his bored stare toward them. It seemed to Eli as if today's non-stop action had made any moment for this man that wasn't spent shooting holes through alien creatures as tedious as watching grass grow. The Black Mesa personnel who were clustered in small groups did not seem to share that sentiment. They seemed highly strung.

'The aliens have stopped teleporting – finally. Now that Black Mesa is rubble, command has decided to transport all surviving employees to a secure location where they will be informed on how everything which occurred today in Black Mesa must remain top secret.'

Eli thought, but did not say, that it might be safer for the government to kill every scientist there, as had been their original plan, ensuring their silence. Eli wondered if that really was their plan. Perhaps once they had been transported to this 'secure location' they would all be lined up against a wall and shot.

Eli and his daughter had been through much today for it to end like that. Maybe it would be better to try and slink away now. He was about to assess the possibility of doing just that when someone caught his eye.

'Izzy!'

Dr Kleiner detached himself from whichever gaggle of science team members he had been conversing with and whirled around upon hearing the sound of the name only Eli ever called him by.

'By Schrödinger's cat!' he exclaimed. 'Eli, you survived!'

He looked down, seeing Alyx for the first time.

'And you found dear Alyx! Oh, this is wonderful.'

He gazed about in several directions.

'And where's…'

He had clearly expected to see Azian with them, but looking back on Eli and Alyx's forlorn and exhausted faces, he realised his faux pas.

'I see', he murmured. 'I'm so terribly sorry.'

Kleiner shared their grief. He had known and liked Mrs Vance.

'There'll be time to mourn later', said Kleiner. 'The day isn't over yet. One of the lieutenants told us to remain in Encino until the transport helicopters get here. We'll all be taken back to the nearest military base and instructed on how everything that happened here today should be handled.'

Eli looked around tentatively, making sure that no nearby soldiers could hear him.

'Izzy, aren't you worried at all that there's more on the military's agenda than rescuing us. Who's to say they won't revert to their original objective and silence us in the most decisive way, by killing us.'

'It's over now, Eli. I think the top brass were worried when they discovered that actual aliens were crossing over into our world, and gave the reckless order to wipe out Black Mesa completely. The worst is over now.'

Eli was not convinced, but Kleiner continued.

'Besides, did you hear? Gordon Freeman, the very man we sent into the test chamber this morning, spanned the gap into the other world – our colleagues from the Lambda Complex told me they were calling it Xen – and destroyed whatever was keeping the portal open.'

'So Freeman is stranded there?'

'I'm afraid so. The brave man gave his life to ensure the safety of our world.'

Eli found it hard to believe that there would be no further fallout from the Resonance Cascade, though maybe it was true. Presently he could hear the blade slap of the transport helicopters approaching in the distance. Every head on Encino's main street turned to look in their direction.

All the while, Eli was ruminating. It was a miracle that he and Alyx had survived this day. Would he throw his good luck away, be ushered into a helicopter like a herd animal and risk being euthanised? No. He had Alyx to take care of and he wouldn't be doing his duty as a father if he put his daughter in harm's way once again. Keeping a tight grip on his little daughter's hand, he turned to his colleague.

'Izzy, I think we should—'

All of a sudden, the ground began to shake and Eli could hear a deep rumbling. At first, he thought the sound was coming from the helicopters, but it was far too low and distant. He looked back the way he and Alyx had come, towards Black Mesa. From the remote facility's smoking ruin a flash of light issued forth, like a great glowing cloud, electric-blue. It ballooned in size, the rumbling intensifying, then resolved itself into a wave of vertical streaks of light.

'It's like a storm', gasped Kleiner.

In an instant, the wave emanated outward from what was left of the facility, travelling fast across the flat expanse of the New Mexico desert. There was no time for anybody to run. The wave was upon them in seconds and Eli pulled Alyx close. All they could do was brace themselves.

For half a second, everyone on Encino's main street felt a strange sensation of weightlessness, although the ground at their feet was quaking all the while. The wave passed through them, then surged toward the still-airborne helicopters. On them, the storm had a different effect. As soon as it pervaded the aircraft, they lurched sideways, some at odd angles, and careened towards the red earth, crashing and rupturing, shattering their rotor blades.

Even then the storm hadn't finished doing its damage.

'Look, the bridge!' shouted a hysterical voice, and the onlookers turned from the ruined husks of the helicopters to Encino's most notable structure. Its abutments, rails, and girders were giving way under the pressure from the strange phenomenon. Thankfully, there were no vehicles on the structure, but debris dropped onto the valley below, throwing up great clouds of dust, leaving only a few remaining supports twisted at odd angles where the bridge had been.

After the blue wave had passed far into the distance and the dust from the bridge had settled, a brief silence spread throughout the group, followed by nervous, hushed conversations.

Alyx was gripping tightly onto her father's hand, pressed against him, as she had been since the strange storm had started.

Kleiner turned to Eli.

'What was that? What does this mean?' he said.

Eli said: 'That storm came from Black Mesa. It's the aftermath of the Resonance Cascade.'

Kleiner's voice was urgent: 'But I thought all that was over. Our colleagues at Lambda said Gordon had put an end to all this.'

'I get the feeling this isn't the end', muttered Eli. 'This could be the beginning of something far worse.'

In the distance, the survivors of the Black Mesa incident could hear the remote sound of something echoing across the oblate desert from the debris of their destroyed facility, something hateful and utterly alien.

'We have to leave now', Eli said to Kleiner. 'We're sitting ducks here.'

'You can't seriously think the aliens are back', said Kleiner fervently. 'The rift was closed.'

'I don't have any answers, Izzy. Today has been full of surprises and horrors. I only know what I can hear, that this violent storm has brought with it even more alien creatures. Now let's go.'

With his friend and the only remaining member of his family, Eli set off eastwards, in the opposite direction they had come from Black Mesa, warily bypassing the destroyed remains of the fallen helicopters. Slowly, the rest of the former employees of the facility began to trickle out of Encino in the same direction. Nobody was certain if the nightmare they had all experienced that day would continue into the future, but all were prepared for the worst.