Alyx could hear them everywhere now. Black Mesa was alive with unearthly activity. Some seemed to have crept out of the darkness of dormitories whose doors had been left ajar. At first, she thought they were more of the shambling figures whose heads had been eroded by the crab-aliens, brains subdued by them, and surely some of them were, but now she could hear other sounds: the soft scuffling of headcrabs searching for hosts, the brisk, canine scampering of those tripedal creatures whose manifold, beady eyes took in everything around them, the hunched humanoids who Alyx, peeping out from behind the dumpster, almost took for human. They travelled in small groups. She could hear them speaking to one another in husky, guttural voices; surveying the area for human life, then disappearing as Alyx hoped they would.

She hadn't moved from her spot, instead begging for the nightmare to end, for herself to disappear and vanish into nothingness, to return to a world where horrors weren't shuffling around every corner. She had been extremely lucky that all the monsters had kept to the wide-open areas of the dormitories, not thinking to look in the secluded passageway where the dumpster and trash cans stood. She now wished she hadn't run away from her teachers and classmates. Maybe if she had stayed with them she would have been reunited with her mother, and maybe even her father.

She couldn't stay here forever. Sooner or later she would need food or to use the bathroom. When that happened, necessity would drive her back out into the open, where all the monsters were, and one of them would catch her, be it shuffling zombie, croaking alien, or the small crabs which leapt at heads. She feared the latter the most. What it must feel like to have one of them clamp its thorny underside onto your head. Images of the first zombie she had seen in her neighbour's apartment flashed before her. The crunching sound, the blood running down its torso. The frightful memories were almost too much for her young mind. It made her want to start crying again, but she knew it would do no good. It might even attract some of the monsters if she sobbed too loudly.

Much time passed. Alyx had not heard a noise for quite a while. She had to move now before the dormitories became busy with monsters again. She was just about to peek around and creep out of her hiding spot when she heard footsteps. They didn't drag against the ground as they did with zombies, nor did they make clunking sounds as they did with the hard-toed aliens. Perhaps it was something new?

Alyx pressed herself into the corner between the wall and the dumpster as much as was possible and held her breath. The steps quietened but nonetheless seemed hurried, frantically moving over the open space of the dormitories. Finally, they moved closer to Alyx's hiding spot. She pressed her eyes shut, took a deep silent breath, and willed the creature to leave, to move away.

The steps slowed, yet moved closer all the same, now right next to the waste bins. Alyx's heart was pounding. This was it, she would be discovered now, and God knows what the monster would do to her.

The creature stepped out in front of her, and Alyx heard a very human gasp. She opened her eyes.

'Mom!'

Azian Vance pressed her finger to Alyx's mouth for quiet, her eyes shining with joy and relief. Mother and daughter gathered themselves together, tears falling from their faces.

'Oh God', cried Azian quietly but fervently. 'I was sure you were dead. When they told me you weren't with the kids and teachers who were evacuated I knew you must have snook away.'

'I'm sorry Mom. I was worried about you and Dad. I should have stayed with the class.'

'No. I'm glad you didn't. I went up to the surface with everyone else in the dormitories. Soldiers came as we got to the surface. Everybody thought that they were here to rescue us, but they started rounding everyone up, and rumours began to spread that they were here to silence us instead, so I left the group when they weren't looking, just like you did.'

'Will they come down here to search for you?'

'I don't think so. It's overrun with aliens down here. It's a miracle I made it as far as I did, and a miracle you survived. The creatures down here are too strong. They'll probably assume we are already dead. The soldiers are already leaving because they know they can't win against all the monsters down here.'

Azian drew Alyx up onto her feet, tears still in her eyes.

'I'm so glad I found you, baby. But we're not out of danger yet. Keep quiet. There are still aliens everywhere, and sometimes they appear out of nowhere.'

Azian thought about returning to their apartment to salvage some things, but it wasn't worth the risk. It was entirely possible that some of the headcrabs had materialised into the neighbouring apartments and had found and assumed control of hosts.

Alyx told her about the zombie she had encountered in the dormitory to the right of their own. About what the crab had done, the noise it made, and how it and risen to its feet and advanced upon her. Alyx's voice was shaky with fear and sadness as she told the story, and as Azian listened she was surprised to find she felt not only pity for her daughter, but also anger for the person or thing responsible for letting Alyx experience horrors no five-year-old should have seen.

Azian asked herself the same question which no doubt most of the survivors in Black Mesa had asked: What was the root cause of this disaster? Who was responsible? Had it been alien intellect alone which had devised this disaster, or something humans had done? Azian suspected the latter. She arrived at the notion that it probably had something to do with Eli's experiment, though she knew her husband would never willingly bridge a gap between a hostile world and their own.

She recalled all the times Eli had confided in her about the upcoming experiment. His anxiety, his fears, his strange nightmares. Maybe, Azian thought, it would have been more prudent for him to give in to his fears, staying at home instead of swallowing them and going to work in Anomalous Materials that morning.

And yet, Azian got the sick feeling this disaster would have happened whatever Eli had done. Human beings may have taken part in the inception of this disaster, but they were human beings who were being used by some greater foreign power, dallying like puppets.

Azian, Alyx, and almost everyone in the facility of Black Mesa, were feeling the disconnect between past, present and future. Between the quotidian, relaxed life of that morning, and the utter ignorance of what was going to happened next. Would the alien attack end today in Black Mesa, or would it begin to happen everywhere, worldwide. Azian had no idea what would happen next. She just knew she had to protect her daughter, find her husband, and stay out of harm's way.

These were Azian's thoughts as she padded softly and silently through the facility, hand in hand with her daughter. So far the place seemed to be mercifully quiet. Azian willed the place to remain so. She didn't want any more gruesome and horrific scenes to present themselves before the frightened five-year-old.

Where to go next? She had a choice: Continue to look for a path through the facility which was alien-free, or take a risk and return to the surface where there could be both foreign life-forms and soldiers, undoubtedly fighting there. But the transit system was out, and if Eli was searching for them, and he certainly was, then he would have found his way to the surface too, trying to find a passage to descend to the dormitories. Though it was hazardous, Azian decided to ascend to the surface was best.

She looked down to Alyx, who was still gripping her hand firmly. Her expression was tense, no doubt masking further fear beneath the surface. Now and then her head would dart in a different direction, in case there might be aliens in the distance.

'Baby, you've been very brave today. You're such a brave girl. I need you to stay that way for a little longer, okay? We're going to look for Daddy. I'm sure he's looking for us too. We'll find him on the surface.'

Alyx responded by shaking her head briskly and gripping her mother's hand ever tighter.

The emergency evacuation passage was deserted once again. This was the third time Azian had used it today: Once when she followed the other civilians when the alarm had first sounded, once when she climbed back down to look for Alyx, and now once more, hopefully for the last time.

The ascent took the form of a concrete stairwell. After several flights of stairs, Azian would have complained about aching calves and knees, but she was far too frightened and wary of her surroundings to think about such things. Alyx however was much smaller, and the steps were larger for her than they were for Azian, so halfway to the surface Azian gave her a piggyback. Her daughter's tense grip around her shoulders spoke of her fear. Azian even thought she could feel her trembling against her back.

After a great many flights of stairs, Azian looked up to find she could see natural light flooding into the narrow space from above. It was the surface. She had just put Alyx down, telling her they had finally reached the top, when she heard the sound of a great explosion, the ground shaking, earthquake-like, causing mother and daughter to be thrown to one side, inadvertently sliding down a few steps.

The concrete ceiling above them began to crack. Azian watched the fissure rapidly move along the surface, before turning away, picking Alyx up, then hurtling through the doorway and into the light. The passage collapsed behind her.

Several sights seemed to assail her all at once. Her gaze drawn upwards, she watched two fighter jets surge through the sky, dropping bombs onto some distant part of the facility, though Azian felt the ground shake under her feet nonetheless.

Then she looked down from the sky at her surroundings, and what she saw horrified her. She pressed Alyx's face against her so she wouldn't have to see too. The small group of civilians who she had been evacuated from the dormitories with were slumped against the wall. Its whitewashed surface contrasting with the blood it was bespattered with. Some of them had been her friends, their bodies now torn apart by bullets. They had been executed by firing squad, though Azian saw no sign of the military now.

However, she could see all the signs that they had been here. Sandbags, military crates, and a radio with two large antennae. She could hear the soft sound of an extremely distressed voice coming from it. She moved closer, turning the volume dial clockwise.

'Forget about Freeman! We are cutting our losses and pulling out. Anyone left down there now is on his own. Repeat, if you weren't already, you are now…'

Freeman?, thought Azian. Wasn't that one of Eli's colleagues? A new recruit? Why would the military be interested in him? It didn't matter. Azian shook the irrelevant thoughts from her mind.

More fighter jets streaked overhead, releasing yet more explosives onto the facility. They couldn't afford to dally here any longer. Sooner or later they would start dropping bombs directly onto her and Alyx. The army was laying waste to the entire facility.

The facility belowground was infested with aliens, the surface was being bombed. Where was safe? Where would Eli go? A vague memory drifted out from the fog in her mind. The Lambda Complex. Eli had mentioned that before. It was underground but extremely secure. Some of the aliens might have winked into existence down there, but it would likely be safe from bombs. But Azian had no idea how to get there. All they could do was keep moving and hope to find a way through.

Azian put Alyx down onto her feet, making sure she didn't look back at the carnage behind them. The heat of the midday sun caused sweat to bead on her forehead and run down to her eyebrows. The two of them were used to being cool, underground.

The surface was a confusion of concrete buildings, many of them reduced to rubble by the explosions. There didn't seem to be any rhyme or reason to where the bombs were being dropped. The military were scattering explosives all over Black Mesa. Azian felt like a rat in a maze, a maze in which there could be things trying to kill them.

Turning one corner, they found their luck had run out. They approached a wide-open space with a helipad in the centre, and several soldiers surrounding it, obviously wary of encountering aliens approaching from any direction. A transport helicopter was just touching down, clearly picking up the last of the stranded soldiers before the rest of Black Mesa was reduced to debris.

Suddenly, several monstrous aliens of a sort Azian had never seen before barged through a heavy door which seemed to have been locked and barricaded, though it did little to hinder the soldier's attackers. They were dark grey-skinned and armoured, taller than any of the men now scrambling aboard the helicopter and urging it to take off. The soldiers opened fire, some of their bullets implanting themselves in grey flesh, sending green blood spurting, others ricocheting off of dark blue metal. Several aliens went down, riddled with bullets, but more kept coming. Azian and Alyx watched small but fast objects streak through the air, curving and leaving trails before they implanted themselves in human flesh.

Nonetheless, the helicopter had lifted off and was now gaining altitude as the wide-open space flooded with more of the same aliens. It looked to Azian like the aircraft and those in it had almost freed themselves from the alien assault when a clanging came from the door the other aliens had broken through. The clanging grew louder, and Azian thought the doorframe must be breaking apart to let something much bigger in. She was right. In a moment, a monster that must have been 20 feet tall stepped through the rubble it had just created, crunching the corpses of its consorts underfoot. Its arms ended in open pincers, the inside of which glowed red hot. The air in front of its limbs wobbled and distorted the air. It trudged noisily over to the airborne helicopter which was only just within its grasp. One pincer closed on a landing skid while the other remained open, letting out extremely torrid air. With a great wrench, the creature pulled the aircraft down, closer to the ground and started to melt it with the heat from its open limb.

Metal began to buckle and warp, and the marines, having no other option, abandoned the helicopter which had been there to rescue them. Flesh sizzled and camo gear began to burn. Several soldiers dropped onto the helipad, their bodies engulfed in flames.

Azian shielded her daughter's eyes, but both of them could hear the screams of the humans from where they were standing. Today was proving a difficult day to protect Alyx's senses from things no five-year-old should experience.

Now the aliens were finishing off the remaining soldiers, the helicopter being torn apart by force and extreme heat. Neither Alyx nor Azian needed to see any more. Azian was about to turn away when she spied a figure on a platform high above the open space surrounding the helipad. It looked human. A man in a blue suit carrying a briefcase. The aliens should have been able to see him. He was clearly visible, but they were ignoring him. Azian watched him gaze down at the catastrophe below, then he turned his head and looked straight at her. His fixed stare made her flesh crawl. Azian, turning away and pulling Alyx by the hand, began to reach frantically for some way forward, but it seemed the luck which had kept the creatures at bay, and them safe from harm, was finally running out.

Azian could hear heavy, laboured, and foreign footsteps coming not only from the helipad area but from every direction, from around corners, out of doorways to buildings she did not recognise. Alyx began to cry. Azian darted for a warehouse door and, pulling her daughter along and glancing fearfully inside, she determined it was empty, though it wouldn't be for long. They needed somewhere to hide.

The place was thankfully replete with crates. Perhaps they could hide in one?

It was too late. There was no time to hide. One of the brawny aliens had spotted them and was already wedging his hulking body through the door. There were a great many of his kind behind him, their red eyes burning with hatred, cruelty, and hunger. Azian had never been so terrified in her entire life, not just for herself, that alone was bearable, but for her daughter.

Alyx, I've failed you, she thought. I'm so sorry, baby.

Once more she had pushed Alyx behind her, shielding her with her body. They backed towards the far corner of the room. There was no window to jump through, so hatch or hidden door to make a break for. There was only the confined space of the Black Mesa warehouse and its cold, concrete walls.

Now several of the bulky aliens had filled the room and continued advancing. The ones closest to her were standing three abreast in the narrow warehouse. They began to lift their weapons, but they did it slowly, sluggishly. It seemed to Azian as if they had suddenly decided to take their time in killing her and her daughter, relishing it.

Some voice at the back of her mind which managed to speak over the abject terror throbbing in her brain was telling her that something was wrong. Something was slowing them deliberately.

The space around them grew dark, as if the air was taking on a more sombre, denser form. The mammoth aliens incrementally lifted their weapons until they were pointed directly at mother and daughter, then came to a complete stop.

Out of the darkened air, from behind or perhaps through the aliens, Azian couldn't say, walked the man she had seen just moments before.

'Mrs. Vance', came his shaky voice. 'I see you are in quite the – predicament.'

Azian had no idea what was happening. Was it this man who had caused the monsters to freeze in place?

A blue-suited, grey skinned figure of a man strode forward. The voice was coming from him. He did not walk around the aliens surrounding them but through them, as if the monsters were not really there.

'Help us!' she called out. 'Please God help us. Help my daughter.'

Fearing for Alyx more than anything, she pushed her sniffling, terrified daughter towards the man in the suit who appraised them with his incandescent green eyes, looking for all the world as if he had witnessed this scene play out already a hundred times.

Alyx dimly recalled seeing this man before. Had she spotted him while taking the tram to the dormitories?

'Help you? – Hm – I am afraid you misunderstand the situation, Mrs Vance', spoke the strange man. 'I help only those whom I believe in future might be worth something to me and my – hm – employers. Promising investments, you understand. Much of the time, the worth of one human life is much like another. Could you hazard a guess as to how many human lives have been lost today?'

'Then you're one of them', spat Azian. 'You're one of the aliens.' She pulled Alyx back, closer to her.

'A-liens?' utter the man, in a half-gasp, half-laugh, as if the word was entirely foreign to him.

Now, looking down on the five-year-old, as if seeing her for the first time, he spoke: 'Perhaps letting this – hm – child die here would be a wasted opportunity. Perhaps she could be of some use in future.'

'Please take her!', cried Azian fervently. Take her to her father.'

The man was not listening. He said: 'Yes. As of yet, the girl is quite worthless. I have nothing to lose by plucking her here and depositing her safely elsewhere, though I am sure there will be dissenters.'

'And me', said Azian. 'Can you take me too?'

'I am afraid you misunderstand the situation, Mrs. Vance.' In his voice there was neither pity or sympathy.

Azian understood nothing of who this man was, whether he was on their side, whether he was even human, but today had been a day full of incomprehensible events. All she knew was that at one minute they had been backed up against a wall, staring death in the face, and the next, someone had intervened. If this strange man could do that, surely he could affect Alyx's fate.

She gazed at her daughter with tears in her eyes. Alyx gazed back.

'Please take me too', Azian said to the man, still looking at her daughter.

'You are merely not worth taking, Mrs. Vance. I would be severely upbraided for more than one potentially useless individual. I am sure you will understand.'

Azian did not understand, but she wanted her daughter to live, so she pushed Alyx once more, gently toward the man, who laid a hand upon her shoulder.

Fresh tears began to brim from Alyx's eyes. She began to understand that she would be leaving her mother.

Azian released her grip from her daughter. The man in the suitcase looked at Azian with a strange expression of satisfaction.

'Thank you, Mrs. Vance.'

Azian gazed at her daughter for the last time, whose aspect was no less terrified, distressed and uncomprehending. Now the man and the girl began to fade, the thick darkness began to dissipate from the air, and the pitiless aliens became clear in front of her once more, their limbs and bodies starting to move again.

Azian Vance looked death in the face.