Hiya folks! Sorry for… yet another late chapter. I'm still sick, believe it or not, and this sickness is really sapping my energy. I think I'm starting to get better though, so hopefully the next chapter will be posted on time.

Anyway, without further ado… let's introduce a new character (or two)!

Somewhere in the facility, there rang out a quiet, solitary beep.

This was not unusual for the facility, where there were thousands—possibly millions—of machines performing hundreds of different actions simultaneously. There were beeps, clanks, hisses, whirs, artificial voices chattering amongst each other—truly the facility had a sense of liveliness to it, almost like a bustling city, despite nearly everything within being entirely artificial.

But what was unusual for the sound was that it came not from the lively upper floors of the facility, but from its depths, deep toward the bottom of the salt mine. There, the only sounds were the dripping of toxic sludge, the groans of rusty metal as it slowly decayed, and the mournful caws of lost birds. If the upper facility was a lively city, the lower facility was the ruins of one.

The sound came from one of many small structures that had recently been moved into the depths of the facility, the rooms sitting like rows of little boxes next to a towering, rusty shaft. Each box was about the size of a small bathroom, and indeed, they all had toilets. But unlike a bathroom, each of the boxes also contained a pod-like bed, a nightstand, and a few objects that were damaged beyond recognition. Aside from one panel, the walls of the rooms were made of glass, though too old and foggy to see out of.

What separated one of these structures—the one that had emitted the noise—from the others was two things: a dusty, battered cube sitting on the floor, and a human being sleeping within the pod bed. With another beep and a quiet hiss, the shield on the bed slid open, and Doug Rattmann blinked into consciousness.

Drawing in a deep breath and letting it out in a groan, the human slowly rose and winced at the stiffness in his back. His spine popped and clicked into place as he turned, blinking wearily at the fluorescently-lit room. "Where…?" he muttered, his voice barely a whisper.

As he waited for the fogginess to lift from his mind, he rubbed his hand through his hair and across his face. His hair was still the same length he remembered, and his face still gaunt as ever. But his brow furrowed in confusion as he wondered just where he was and how he'd gotten there.

You're awake.

He started at the voice, looking down at the floor beside the bed. The voice was entirely human, yet there was no human beside him—only an old cube.

…The cube!

Everything came back to him in a rush—the explosion, the turrets, the extended relaxation center—

"W-we're… still alive?" Doug stammered, rubbing his eyes in amazement. "I can't believe… the relaxation centers don't usually keep test subjects alive for this long." He paused, drawing in a breath. "But how long have we—?"

I'm afraid I've lost track of time, but it's been a while.

Doug stretched, feeling his joints pop and crack, and tried to move his legs. Immediately he cringed at feeling a dull pain and stiffness in his right thigh. "Agh—!"

Be careful. Your leg is still injured from the turrets. The Companion Cube seemed to bend toward him as though looking him over. I'm not sure if the bullet is still embedded.

"I-it should be," he muttered, finally pulling his legs out over the edge of the bed. "But it seems like it would be hurting a lot more if it was." Reaching down, he pulled up his right pant leg up to the thigh to examine the wound, and gave a start.

…Oh.

"You… you didn't see anyone…?"

I may have… dozed off a few times.

Doug stared. Where there should have been a nasty bullet hole in his leg, there was an old bandage tightly wrapped around it. With shaking hands, he managed to untie the bandage, revealing a scar where the bullet had hit. "One—one of the med-bots has been in here," he muttered, pulling the pant leg back down. There was still a hole in the fabric.

Resting his elbows on his knees and his chin in his palms, the scientist stared down at the ground in bewilderment. While he wasn't ungrateful about being patched up, something about the whole thing made him uneasy. Back when they regularly tested subjects, if a subject actually survived a round of testing, they would be brought back to the relaxation center where a med-bot would clean up whatever wounds they might have in order to preserve them for further testing. But…

"This isn't adding up," he said, lowering his hands. "We came here after she was taken down."

Perhaps other parts of the facility were left running. The cube hummed in thought. The turrets certainly were—and obviously this chamber was. Is it that unreasonable to assume other robots were still functioning?

"No, I guess not." Doug heaved a sigh. "Still doesn't explain what's going on here."

Let's have a look outside, then. The cube bobbed in the direction of the door. Perhaps that will give us some answers. It watched as the scientist began to ease himself off the bed. Watch your leg; it may still be stiff.

"Yeah," Doug grunted, easing himself to the floor. His leg was indeed somewhat stiff, but then, so was the rest of his body. It would get better as he continued to move around. Glancing at the cube, he bent down, motioning to it. "You coming?"

Of course.

Soon his friend was at its usual spot, hovering directly behind him. With a satisfied nod, he rose to his feet and approached the wall, limping on his right leg. "Maybe we can get out of here this time."

Maybe. If there's anywhere out of here to get to.

"D-don't say that," Doug muttered. He felt around the wall and opened up a small patch, revealing an input panel, into which he typed a command. He hesitated, finger hovering over the "enter" key, and closed his eyes before pressing it. With a dull beep, a section of the wall swung open.

Oh my.

Doug opened his eyes and staggered backward. "Wh-what—?!"

The sight that greeted him was not that of the facility he remembered. Instead of dusty, half-destroyed hallways and trails of dried blood, there was a dark, cavernous expanse with an enormous shaft just ahead, a number of others barely visible in the darkness beyond, ancient buildings around him, rusty catwalks connecting the different structures, and a lake of an unidentifiable substance bubbling far below. The air was stale and bitter, smelling of rust and chemicals, and dust stung at Doug's eyes.

"Wh-where the heck are we?" he gasped, struggling to keep his legs from giving out from sheer shock. "This—this can't be the facility…!"

Perhaps it has been a long time, the cube remarked, poking out from behind his back. Or perhaps we've been moved.

"No, the relaxation chambers only ever get moved between the vaults and the testing tracks. This is neither." He leaned against the doorway, his jumbled mind refusing to take in the sight before him. "Am I just hallucinating this…?"

No, I can see it. I can also see other relaxation chambers.

Doug gave a start, finally poking his head out of the chamber. Sure enough, his chamber was lined up with a number of others, all connected by catwalks. "But this isn't the relaxation vault. This is nothing like the relaxation vault." Tilting his head back, he tried to find the ceiling of this strange place, but he only saw the enormous shaft, the top of which faded into the darkness above.

Was Aperture not built in an old salt mine?

"Yes, but… are you saying we're all the way down there? In the original mine?" He shook his head. "This was all sealed off years ago—we can't have been moved down—down here, I-I don't—!" His legs began to tremble before finally giving out, bringing him to his knees.

Calm down. There must be an explanation for this.

"There is," Doug breathed, "but I get the feeling… we're not going to like it."

When have we ever liked anything about this place?

He snorted. "There was definitely a time." Hanging his head, he stayed on the floor for a while, trying to focus through the confusion in his mind. Without warning, another memory snagged him, and he bolted upright. "The girl—!"

The cube took a moment to respond. We left her in cryosleep. She is likely still there.

"We need to get her out of there," he said, shakily rising to his feet again. "Wherever we are, it's probably not where she is, unless you see any of the extended relaxation chambers here."

I don't.

Doug drew in an uneasy breath. "Then let's go." With that, he stepped out of the relaxation chamber, the cube hovering after him. The catwalk shuddered under his feet when he stepped onto it, and he went still, gripping the railing until he was sure the floor wouldn't give out from underneath him. Once the catwalk was steady, he carefully moved forward, heading toward the path that led to the entrance of the shaft.

As he got closer, he found a gate blocking the path to the shaft. Frowning, he approached it and examined it closely. There was a lever next to it, but he got the feeling it didn't open just the gate. "There's something odd here," he muttered.

It may open the hatch to the shaft,the cube noted.

Doug peered through the gate, noting the absolutely enormous circular hatch covering part of the shaft. He then looked up, trying in vain to see the top of the shaft. "Do you think it goes to the upper facility? I-if we are in the original mine, anyway."

Only one way to find out.

Drawing in a breath, Doug reached out toward the lever, grabbing it and pulling it down.

BEEP… BEEP… BEEP…

The sound was almost deafening in the thick silence of the cavern, and it was compounded by the alarm that whined over the noise. Doug staggered backward, nearly bumping into the railing behind him, and whipped around, fearing that he'd awoken some ancient horror from the noise. His sunken eyes were wide with horror as he looked around as spotlights swung around the cavern; he half-expected vents to open in the distant walls and begin spewing neurotoxin at any moment.

A deep groan rumbled behind him, and he turned again to find the gigantic hatch grinding upward on its rusted hinge. Slowly it rose up, up, casting an ominous shadow over the entrance to the shaft. All the while the metallic groaning grew louder and louder, and Doug had to cover his ears for all the noise.

After what seemed like an eternity, the hatch finally rose to its peak, and simultaneously the alarms fell silent and the spotlights faded. Several lights came on with a loud slam, illuminating the darkened shaft and displaying what the hatch had been hiding:

An average-sized door, a folding chair, and a couple broken bottles of pop.

The gate to the catwalk opened with a cheerful squeak, allowing Doug to continue down the path… which he would, once he got over the completely anticlimactic spectacle he'd witnessed. He let out a sigh he'd been holding, resting his hand over his pounding heart. "Sometimes… I think I have this place figured out."

And then something like that happens.

He shook his head and carefully moved forward, looking between the catwalk and the raised hatch to make sure neither of them would suddenly drop. Once he reached the entrance to the hatch, he pushed the door open, stepping in and looking around warily.

The shaft was poorly lit, and he could barely make out a number of enormous spheres suspended above, casting eerie shadows on the catwalks below. The spheres were connected both by catwalks and ancient lifts, and continued upward until they faded out of sight. Meanwhile, the bottom of the shaft was flooded with an unidentifiable substance that reeked of chemicals. From the distance came echoes of water dripping into the pools; the only other sound was a faint metallic groaning from somewhere in the depths.

Doug could not move forward.

"This is one of the old testing shafts," he whispered, as though to keep the spheres looming above from hearing. "It's not safe here."

It's not safe anywhere.

Some ominous, high-pitched noise rang through his mind, and he could feel his breathing quicken and his bones shake. "People have died in these shafts."

People have died upstairs.

The sound grew louder. "No—even employees running the spheres were injured and killed. We have to get out of here."

And go where?

"There—there were other catwalks—" The sound in his head was deafening, and he whirled around to make a mad dash out of the shaft—

Look out!

—and stopped just in time to avoid being hit by the hatch to the shaft as it smashed through the catwalk, nearly sending him flying. Frantically he grabbed onto the rails of the broken catwalk, watching in horror as the hatch fell into the depths of the mine. It was a good ten seconds before he heard the tremendous SPLASH as it crashed into the lake below.

The sound hadn't been in his head; the hatch had rusted completely off of its hinge.

No turning back now.

"…Right," Doug panted before crawling to the safety of the shaft's entrance. "Right."

After taking a minute or two to recover from the shock, he rose to his feet and took another look inside the shaft. Parts of the catwalk were destroyed—possibly rusted away, or else smashed by parts of the ceiling falling from above—but one path still led to what appeared to be a structure with yellowed windows. Out of one side of the structure was yet another catwalk, which led to a lift that went to the lowest sphere. Along the path to this building were signs warning of the dangers of the lake below, displaying a silhouette of a man being dissolved in acid. Doug frowned at these, keeping an eye on the catwalk below as he crept toward the building.

"How many people died just from a simple misstep here?" he muttered.

Do you really want to think about that?

Doug shook his head as he approached the door to the structure. There was a date above it, but it was hard to make out—while he could clearly see the "19," there was a hole in the wall that mostly obscured the last two numbers. Squinting his eyes, he managed to make out a "5" as the third number, but gave up on the last one. He then turned to the door, opening it and cautiously peeking inside.

A pitch black room greeted him.

"…Did you see another way to those spheres?"

No.

Wincing, he pushed open the door further, allowing the feeble light from the shaft to illuminate part of the room. He had to stand there for a bit to let his eyes adjust to the darkness, but finally he managed to spot a switch on the wall. Slowly he inched forward, making sure the floor wouldn't give out and drop him into the toxic lake below. As he reached toward the switch, he glanced back at the doorway, readying himself to bolt if something went wrong. Once he was sure he could get out soon enough, he grasped the switch and pulled it down.

Immediately the entire building was flooded with light, illuminating an enormous room that might have looked impressive in its heyday. Enormous letters reading "APERTURE SCIENCE INNOVATORS" with the 50s Aperture logo hung from the ceiling, though now it looked more like "A PER U E SCI C IN OV T R ," for nearly half of the letters had crashed to tiled floor below. One side of the room was covered in yellow-fogged windows, through which two or three lifts to the surface—all with "out of order" signs plastered onto them—could barely be seen. Stairs led up to a smaller office, possibly a check-in point, which led elsewhere.

Doug might have stood back to appreciate this sight had it not been for the blaring, off-key music that exploded from the ancient speakers shortly after the lights came on.

"WwwEEeEEElc-c-c-c-come to APerT-T-TURE S-S-S—ence!" stammered a warped voice over the music. A few glitched, static-filled squawks spurted out of the speakers before the voice and music resumed in a normal key: "—Johnson, CEO of Aperture Science. You're here because we want the absolute best test subjects, and you are it!"

During this slight pause in the pre-recorded speech, Doug leaned against a nearby wall, draping his arm over his eyes. "Didn't think I'd be hearing that voice again anytime soon," he muttered.

It could be worse.

"So, who's ready to make some Science?"

"I am!"

"Hah, of course you are, Caroline. Now, we've got some special new Aperture products for you to be testing, so step right up and get to it!"

And finally the music faded, bringing the room back to its usual eerie silence.

Doug winced at the mention of "Caroline"—there was a name he hadn't heard in a while, though the voice sounded much different from what he remembered. And anyway, there was something more important to think about. "Testing, huh?" he muttered, glancing at the cube hovering behind his back. "What 'new' products would they have made in the 50s?"

I'm not sure. The portal gun itself?

"Maybe. Might make for an easier way for us to get out of here… if there's one up there." The scientist cast a glance up at the office above, and with a weary sigh, began to trudge toward it.

His usual caution proved useful as he avoided falling through a few broken stairs, and he made it to the office without much incident. There was a receptionist's desk with several decades' worth of dust covering a pile of faded sign-up sheets, but otherwise there was little else of note there. It was when he continued on into the massive hallway that yet another recording echoed throughout the building:

"Alongside our patented Aperture Science Quantum Tunneling Device, we've begun testing another great new product: turrets! Say hello, little fella."

"Hello."

To your left!

With a cry of horror, Doug dove forward, sliding across the dusty carpet and turning to his left, wide-eyed. He could now clearly see the flickering red optic staring at him through a yellowed glass wall, but otherwise, the turret was still. It was also missing its usual white casing.

"Cute, isn't it? Well, that's just the demo version. Trust me, the real version won't seem so cute once it's firing fifty bullets per second directly at your vitals. That soft voice just lulls you into a false sense of security. Or, that's what it's supposed to do. You tell us! Though if you've got most of your organs replaced with lead, you probably won't be able to do that—but don't worry! If that's the case, we'll know we've succeeded." A pause. "And we'll patch up what's left of you afterward."

Slowly Doug rose to his feet, never taking his eyes off of the construct sitting behind the glass. "Turrets," he breathed. "We had to pick the shaft where they were testing turrets."

At least we know what we're up against, the cube noted, then paused. I can cover for you if you need. I have six hearts to spare.

"No," Doug hissed, finally breaking his gaze away from the turret to glare at the cube. "I'm not letting you get hurt."

I can take more punishment than you can. I was built for it.

Doug shook his head. "We've gone over this before. Y-you weren't the first—" He stopped himself, fighting against the memories from years ago. "No. I'm not letting something like that happen again."

All right. We'd better get going, either way.

The scientist nodded, turning to look down the hallway. There was an old, dusty portrait of Cave Johnson on the walls, but the dust and fogged glass hardly took away from the portrait's charm. It was the CEO in his younger years—long before he'd contracted his fatal sickness. Turning away from that, Doug found a few old benches sitting on the carpet nearby along the path to the testing spheres. It was easy to imagine the test subjects sitting around in eager anticipation, not having a clue as to what they were getting themselves into.

Well, they know now, if any of them survived, Doug thought wryly. With that, he finally began to march down the path, turning back to look at the turret one last time before moving on. As he passed into the next room, another pre-recorded message crackled out of the speakers.

"Before you start testing, we'll need to set you up with some equipment. Now you might have heard rumors of some mystical, space-bending, portal-creating device we've concocted here at Aperture, and let me tell you right now: all those rumors are true! Well, except for the part about the portals occasionally flipping your skin inside-out and turning your livers into rocks. We fixed that last month."

"Mister Johnson—"

"Right, yeah, I know. There should be some Aperture Science Quantum Tunneling Devices hanging on the wall there, so pick one up, strap it to your back, and let's get some Science done!"

"Sir, the equipment?"

"Oh, thank you, Caroline. If you haven't already, change into some of our Aperture Science-branded clothing, free of charge! If you're gonna be test subjects, you should look the part. Don't forget to grab a pair of braces, either. …But bring those ones back after the test."

Doug frowned as the speakers fizzled off. "Didn't realize the liver rumor was true," he muttered. He remembered back in his day—when the scientists were still around—he'd hear all sorts of crazy rumors every week. Nearly all of his co-workers stopped bothering to find the truth behind the rumors, but Doug never did.

It was one of the reasons he was still living.

Are you all right?

Starting out of his introspection, Doug shook himself. "Fine," he mumbled, glancing around the room. "Just some old memories again." He stared intently at some of the empty clothing racks in an attempt to focus his mind on the present.

Hmm. Looks like there's still some devices here.

Turning to the side, he spotted a number of hooks sticking out from the wall, and two large devices hanging from a few at the very end. The "handheld" part of the "Aperture Science Handheld Portal Device" started to make sense as he took in the sight of the enormous shoulder-mounted "Quantum Tunneling Devices." They were incredibly bulky, with a few handles and antennae sticking out of the metal casing, while a hose stuck out from the back. At the end of the hose was what looked like a hair dryer with two triggers on the handle—one for each portal, probably, and no anti-gravity grip. Wonderful.

"I… think you'll have to move for a second," Doug said, glancing back at the cube.

A few minutes later, the cube was rather unhappily sitting atop the portal gun predecessor, while Doug was rather unhappily trying to support himself under the weight of both the cube and the device.

Well, let's hope a test subject accidentally dropped a portal gun that fell through a hole in the floor and somehow made its way down here.

"That's incredibly optimistic of you," Doug grunted, flinching as he adjusted the device's straps. "For once, though, I think I'm grateful for the advances this place made… Whoever came up with the handheld portal device is a genius."

Also dead.

Swallowing at the grim comment, the scientist trudged onward toward the building's exit, hoping the same fate didn't await him in the testing spheres ahead. Nonetheless, he tried to move as quickly as he could before the Quantum Tunneling Device's weight completely wore him out.

Doug was glad he knew better than to take a deep breath as he pushed open the door—the smell of chemicals and stale air was still as bad as ever. He covered his mouth and nose with his hand as he moved over the catwalk toward the creaking lift up ahead. As he stepped inside and pressed the button, he was relieved to find the thing still worked—with a few rusty grinding noises, the lift rose, taking him closer to the sphere looming above.

"Now, your first test is just a simple one to show you how that marvelous device you're wearing works. Should be straightforward. If it's not… I don't know what to tell you."

The lift stopped, and the doors creaked open, revealing the ancient test chamber. Much to Doug's surprise, Cave had been telling the truth: The chamber before him was a single room that was covered in portal-conducting surfaces. There was a sizable gap—too wide to jump over, too deep to climb out of—dividing the room in half, and an exit door on the other side.

If all the tests are this straightforward, we should have no trouble getting back to the upper floors.

"I hope you're right," Doug said, finding himself smiling as he pointed the hairdryer-shaped gun at the wall. One portal on one side of the gap and one on the other, and he was already walking through the exit door and into the lift beyond. Maybe this wouldn't be so bad after all.

"Great job! The fact that you've completed this test means you are not brain damaged—which you shouldn't be, of course, but we have had that happen once or twice. But now in this next test you'll meet your first real challenge. Time to see what that device you've got strapped to you can really do. Hah! See if you can make your way up."

As Cave's rambling came to an end, the lift's gates creaked open to reveal the next chamber. This one had a number of floors between the high ceiling and the lowest level, as well as only a small number of portal-conducting surfaces, one of which was at the bottom of a pit in the center of the room. The objective was simple enough: the subject must use the laws of physics to fling himself up to the higher floors.

No turrets yet.

"I'm not complaining," Doug muttered as he approached the pit. Aiming the gun, he fired at the portal-conducting surface below, then shot another portal at an angled surface nearby. He hesitated momentarily—as any sane person would before jumping into a twenty-foot-deep pit—and stepped forward.

The tails of his worn lab coat fluttered behind him from underneath the Quantum Tunneling Device as he dropped into the pit, and he thought briefly to carefully position his legs so he would land on his feet.

With a jarring change of gravity and a sudden wave of panic, he shot through the portal just as he realized he was missing a key piece of equipment.

"AAAGH—!"

His cry was muffled by a choking noise as he landed incorrectly on his bad leg, sending a wave of pain shooting through the limb. Tears streamed down his face as he began to scrabble at the ground frantically, trying to turn his focus away from the intense pain in his leg.

"Great job, test subject! Aren't you glad you're wearing our patented Aperture Science leg braces? Of course you are—otherwise you probably would've broken your leg or something. And if you did, don't worry. The braces are in the testing stage too."

There weren't any leg braces in the equipment room.

"I—know that!" Doug hissed through gritted teeth. His bony fingers curled around a chunk of debris on the floor, which he gripped tightly until the pain began to fade from his leg. Once he was able to think a little more clearly, he pulled his injured leg closer to his body and felt around it. It hadn't broken, fortunately, but it still hurt like the devil.

After lying there for a moment and wiping the tears from his face, he struggled to his feet, flinching at the pain in his leg. "N-now what…?" he wondered aloud as he looked toward the ceiling of the chamber. There were still two more floors to ascend.

Try to make it through to the end of this chamber and maybe we can find some way to escape.

He shook his head. "I'll break my leg if I try that again."

And you'll starve to death if we just sit around here doing nothing.

Wincing, Doug rubbed his eyes. "Our life is a series of painful options, isn't it?"

I suppose so. Then again, I'm not sure I can feel pain.

Doug grimaced, heaving a sigh as he looked around the chamber again. "I guess you're right, though… Keep an eye out to see if there's some other way out of this chamber, and I'll see if I can survive the rest of this test."

Can do.

With a flash of light, Doug fired a new portal at a nearby raised surface before walking to the edge of the floor. He was even higher above the pit now, but what else could he do? Closing his eyes, he stepped off the edge, allowing himself to drop into the portal below.

As soon as he felt the gravity change, he tried to reposition himself in mid-air, aiming his back toward the floor so the Quantum Tunneling Device would take most of the impact—which it did, but it still jarred his spine. A strained cry of pain tore through his throat, and he stayed on the floor for a moment, breathing deeply.

Are you all right?

"I-I'm not… dead yet…" he gasped. "D-did you see anything…?"

No. I think we'll just have to try to finish the chamber. But… please be careful.

"C-can't… can't make you a-any promises there…" After a few attempts, Doug managed to roll onto his side, wincing at the pain in his back. Just one more floor to go, he told himself as he shot the final portal to another angled surface. Just one more drop…

Struggling to his feet, he gave another choked cry at the pain in his leg and back. Still he limped toward the edge of the floor, looking down at the other portal so far below. "Wh-what if we don't make it?"

I don't know.

Doug looked over his shoulder at the cube, which tilted itself in an expression of worry. He returned the look before turning his gaze toward the portal again and drawing in a breath. "Well… here it goes."

Before he had the chance to hesitate, he stepped off the floor, letting himself plummet toward the portal below.

If we don't make it out of this, I wanted to tell you…

The gravity shifted, and he was flying toward the final floor.

…thank you for not disregarding my advice.

Doug didn't have time to respond as he felt the force of the impact completely knock the wind out of him. He gasped and choked, fighting against the pain in his chest as he lay sprawled on the uppermost floor of the chamber. Distantly, he heard Cave Johnson's voice ringing throughout the sphere:

"Great work, test subject! You're well on your way to completing your tests, and in doing so, helping us win a Nobel Prize or five. Keep it up, and try not to get blasted to pieces during this next one."

He felt the cube lean into his shoulder. Can you get up?

"I—I—I don't… know…" he gasped, still fighting to breathe properly. He tried to get his legs underneath him, but the pain made him think otherwise. "I-I think… I'll j-just rest here… a moment…"

You made it through, at least.

"Y-yeah, but… but what about the n-next… test…? I-if there's any more jumps like that…"

We won't know until we get there.

He shut his eyes, taking in as deep a breath as his body would allow. He could still feel himself flying through the air, the wind rushing all around him as he fell. It seemed like he was falling forever, the portal below him never coming any closer—he simply continued to plummet, waiting to feel his stomach jump with the shift of gravity. He looked up to see how far away the ceiling of the chamber was, then looked down again, only to find that the portal had disappeared, and he heading straight into a cement panel—

Doug started and gasped, feeling as though he'd dropped a short distance to the floor beneath him. He was still sprawled out on the highest floor of the chamber, and his entire body pulsed with a dull ache.

Welcome back. The cube sounded relieved. You've been out for a while.

"I-I thought I was going to be out for eternity," Doug whispered, pushing himself up on his arms. He was still sore, but at least he could move now. Shakily he managed to rise to his feet, and staggered toward the lift. "Do… do you think there will be any jumps in the next chamber?" he asked as the doors creaked shut behind him.

Maybe, maybe not. The lift began to rise. But I think I know one thing that will be waiting for us.

Doug leaned against the wall of the lift and glanced back at the cube. "What's that?"

See for yourself.

A few moments later, the doors creaked open, and Doug's body tensed up completely at the sight of red beams crossing over a narrow catwalk.

Unlike the previous chamber, this one had no true floor—it consisted of a catwalk that went straight from the entrance to the exit, a couple platforms with portal-conducting surfaces, and a single turret sitting atop each platform. Unlike the turrets he was used to, these ones had no pristine white casing—only the black metal framework.

No jumps, at least.

"R-right," Doug whispered, glancing at the far wall and shooting a portal at it. Biting his lip as he turned to face one of the turrets, he fired his gun at the space underneath it.

"Hooray!" the turret cheered as it was suddenly fired through the wall. It sailed over the catwalk it had previously been standing on, one of its stiff legs bouncing against the railing before it plummeted into the abyss below.

Doug stared down after it, hollow eyes growing wide. "That's it."

What's it?

He looked over at the cube, then back at the remaining turret. "If—if I can deactivate that turret without letting it fall, then I can use its parts to cobble some leg braces together—"

Don't be ridiculous! You'll get yourself killed doing that. One step too close to a turret and you'll be dead.

"And I'll be dead if I break my leg!" he cried, shooting a glare at the cube. "What else am I supposed to do?"

The cube remained silent.

Doug winced. "Sorry," he muttered.

…I understand. But I'm more scared of the turrets than I am of falling.

"But you can warn me when I'm within range, right?"

…I could.

Nodding, he continued forward, treading carefully down the catwalk past the spot where the first turret had been sitting. He drew closer to the second one, watching it for any signs of its noticing him. Looking over at the wall to his right and measuring the distance and angle, he fired a portal a foot or so ahead, then aimed his gun at the turret.

It's not going to deactivate until it hits the ground.

His eyes narrowed as he focused, pointing the gun at the turret's legs.

It will still be active when it comes flying at you.

Once he had his gun aimed properly, he turned to look at the portal in the wall.

Be careful, Doug.

His breathing began to quicken, and his hands were slick with sweat—if he moved too quickly, his side would be riddled with bullets, but if he moved too slowly, he would miss the turret altogether. He had to do this carefully, carefully...

He pulled the trigger.

With a frightened cry, the turret shot through the portal, sailing toward the catwalk in front of him. One of its legs banged into the railing on the near side, causing it to flip over onto the catwalk.

The dying fire! Watch out for the dying fire!

Doug rushed forward, scrambling to grab the turret as it opened its guns. Frantically he turned it to face away from himself, too late—the turret began to fire before he could turn it around, and one of the bullets grazed his arm. Crying out at the burning pain that seized him, he fought to keep the turret steady as it continued to fire bullets rapidly in a last-ditch effort to hit its target.

Finally the firing stopped, and the turret's optic faded with a whispered, "Whyyyy…"

Your arm!

"It—it just grazed me," he gasped, dropping the turret and tugging at one of the sleeves of his lab coat. "I'll be all right, just—just give me a…" With a forceful tug, he managed to rip off part of his sleeve, and used the scrap of cloth to tie around the wound in his arm.

Best to take the turret apart somewhere else. You'll lose parts of it if you work on it on this catwalk.

"Yeah…" Wiping the sweat from his brow, he stared down at the deactivated turret prototype lying on the catwalk in front of him. He grabbed one of the legs, lifting it carefully to judge its weight. While it wasn't quite as heavy as he had expected, its weight still added to everything he was already carrying, not to mention it was large and awkward to carry. "Think there'll be space in the next chamber to do this?"

Maybe.

Nodding, Doug made his way across the test chamber, finding himself leaning on the catwalk as he walked—these tests were already wearing down on him, and he hadn't had any food or water in who knew how long. "Hope we can find some drinkable water soon…"

Don't think about that right now. We need to get out of these chambers first.

Finally he approached the lift at the end of the chamber and stepped inside, pulling the turret in with him. He was glad the emancipation grills weren't working in these old chambers—or maybe they hadn't been invented yet.

"Another test well done!" came Cave Johnson's voice over the speakers as the lift began to rise. "Now you've learned how to launch yourself through portals and how to launch turrets through portals! Now, get ready, 'cuz next up, you'll be dodging turret fire as you launch yourself through portals!"

The turret fell to the ground with a loud clang. "What—?!"

"Now I know what you're thinking—'Cave, why should we have to test for something like that?' Well, let me tell you, Science isn't about 'why'—it's—ab—"

The audio crackled and fizzed out before Cave could finish his speech, leaving Doug and the cube to sit in stunned silence.

…Oh dear.

"I-I can't… I can't do it!" Doug cried out, running his hands through his messy hair and grabbing at clumps of it. "We're n-never getting out of here!"

Calm down! We're not going to get anywhere by panicking.

"E-even with leg braces, how are we supposed to make it through—?!"

Before he could finish his statement, the lift's doors ground open with a rusted screech. But the site that awaited him was not what he expected.

Instead of a multi-floor chamber lit by the red beams of turrets, there was part of a floor, half of a few walls, a catwalk that extended for several yards before ending in mid-air, and an empty abyss below.

…We didn't see this side of the shaft when we came in—this whole side of the sphere has been destroyed.

"Wh-what happened?" Doug whispered. "Did it just… rust away?"

I don't think—

The sound of screeching metal tore through the air as something massive fell from the darkened heights. Doug shouted out through the noise, but his voice was drowned by the deafening sound that rang around them. Even so, the cube's voice was clear:

It's part of another testing sphere! They're falling apart—or—or they're being… torn apart! Run for cover, hurry!

"Where?!"

In the lift!

Doug backed up into the lift, huddling in a corner. There were no controls here, leaving him with no escape—just the rusted roof of the lift between him and the monstrous chunks of metal falling from above.

But somehow, over the din, he swore he could hear something—a voice, one that was calling out to him… He usually heard voices, but what if this one was real?

What are you doing—?!

Doug stood, poking his head out of the lift and straining to hear above the horrible sound all around him. He thought he saw something, off in the distance… a light…

"Come this way!"

He didn't know what it was that was calling for him, but it was either follow it, or be crushed by the falling debris.

Before the cube could question him again, he stepped out of the lift.