I swear to God, I had no idea. I feel like such a fool. It would have taken me a second or two to find out, but it just didn't occur to me. And he suffered for it.

He was probably my own age, give or a take a couple years, and wearing a green shirt. The first time I set eyes on him, he was slumped in the corner of a wide cavern. He looked up when he saw me, and his face filled with the familiar relief that I saw in so many eyes. Naturally, I did a visual check as I approached to assess his condition. He was holding his arm to his chest, which spoke of some kind of arm injury, but his legs and torso looked fine, judging by the way he held himself.

"Thank God you're here," he said as I came closer. He spoke a little too loudly, and his voice echoed a hundred times around the cave. I should have seen the signs.

"We received your signal about half an hour ago. Been tracking it ever since. These are tough rocks to get through." I knelt down next to him and put my spare helmet on his head, switching on the lamp, then gently took his arm. "Just going to make sure this isn't anything serious."

He had a large, jagged gash from his wrist to about an inch below his elbow. It was dirty and probably on its way to infection, but we had no time for that now. The paramedics could see to him on the surface, and all I could do for him here was bandage the wound to slow the bleeding. I spoke as I worked.

"You're the last one. We got the last tourist out about ten minutes ago. We're going to get you in the Mole and we'll be back up before you know it." I was looking at his arm as I worked, and he didn't reply. Just watched. "What's your name?"

He took a few seconds, so I looked up and repeated the question. He looked surprised, and I began to suspect he was suffering from mild shock.

"Oh, right. Uh, Benjamin."

"Great." I looked back down as I fastened the bandage. "OK, this is ready. Can you stand?" He didn't answer, so I put an arm around his shoulders, and hoisted him to his feet. He responded to the movement with surprising strength, and stood unwavering. "So how come you were down here alone?" I turned away and started leading the way back through the caves to the Mole.

The rock had become more and more dense as we travelled through the ground. It was packed full as I had never seen before, and the Mole was beginning to struggle. I had to leave it a couple hundred meters back and continue on foot. Luckily, I had stopped in an unbroken part of the tour route, which led right through to Ben's cavern.

"Oh, right. Well, we were further down that way," – he pointed to an entrance on the right – "when the caves started shaking. Everyone scattered. I don't know, I somehow ended up here."

I turned and looked at him, stunned. Was there really such a lack of organization in an official tour? "Didn't the tour-guide giving you directions?"

"If he did, I didn't hear them."

I guessed that that was feasible, if the rocks had made a loud rumbling. But they would have started off quietly, and the tour guide would have noticed... surely?

"OK, the cave begins to thin here. Your light isn't bright, so put your hand on my sash and follow me. Is that all right?"

He took the sash, and I turned and continued leading him down. The cave we were in was not hard to navigate. It had been carved and strengthened for the tours. Still, everything had been dislodged when the first cave had fallen in, and now every rock was as unstable as the other.

"Is it far?"

"No, it's about another five minutes." I didn't like the way he was talking so loudly. Outside, or even in a normal room, he would have been speaking at a normal dynamic level. But with the vastness of the cave behind us, and the unevenness of the walls, every sound we made was echoed and amplified. It didn't bode well for the already weakened walls. "Ben, could you try to keep your voice down? I'm worried about the vibrations."

He didn't reply, and I was beginning to worry. Sometimes it seemed as though he was perfectly with it, and other times what I was saying went straight over his head. As soon as we were at the surface, I was going to get someone better qualified than me to check him over. And with more time.

"I don't tell many people this, but I'm afraid of the dark." His statement came out of the blue, and I wondered if his fear was triggering his strange behavior. His loud voice echoed in the cave.

I guessed he couldn't benefit much from the light on my helmet; instead he was relying on me to guide him.

"It's not – "

"I sleep with the light on," he said, and laughed. He had cut right across me.

"I think a lot – "

"It's pretty embarrassing. I'm twenty-five and I can't deal with the darkness."

What was up with this? First he didn't speak at all, then he wouldn't let me speak. It was like he had no awareness or skills in conversation. He still hadn't lowered his voice, but I could hear it shaking slightly as he spoke.

I stopped and turned, so my light shone on his face. He was pale, but not so white that I should be worried. He blinked in the light and turned away.

"Are you feeling all right?" I said, covering the light partially with my hand to lower the glare.

"What?"

He looked closely at me, and I repeated my query. Then he nodded and grinned. "Sorry. Yeah, I'm fine. Just a bit on edge. Sorry."

"It's fine. We're nearly there."

I turned again and continued, while he took hold of my sash again. "Just try to keep your voice down, OK? It could trigger another rock fall."

We continued in silence for another couple minutes. His breathing was harsh in my ear and my sash was tugging at uneven intervals as he loped behind me. We were about fifty meters away when I became aware of a low rumbling overhead. I kept walking, thinking that if we could just hurry, we could get back to the Mole in time.

Suddenly the loudness went up a notch. I stopped abruptly and Benjamin walked right into me.

"What? What is it?" His voice was loud in my ear, and I shushed him without turning. "What's going on? Sir?" I was growing irritated. Why could this man not understand what I was saying to him? He didn't seem to have any problems in the wide cavern.

"Benjamin, I need you to stay quiet," I hissed, as I continued to listen to the rumbling with a cocked head. I could hear things tumbling, falling overhead. We were about a kilometer down; there was plenty of space for things to shift above us. The walls of this cave were cracked and unstable. But as long as we were as quiet and smooth as possible, we shouldn't have any trouble getting out.

Ben had grown quiet behind me. His callous breathing was ragged, and I could sense his panic. He was trying to keep himself under control. I appreciated the effort and needed to show him that I knew what I was doing, we were so close…

But just as I started moving again, Ben blurted, loudly: "Look, please tell me. I don't know what's going on. What's happening?" I froze. His cry echoed once, twice around us, and then all hell broke loose.

The ceiling caved. My yell was quickly muffled by the deafening sound of rock hitting rock, earth hitting earth. My sash was torn as something huge came between Ben and me, and his hand was ripped from me. I saw a flash of green and heard a yell, before the sight and sound of him was taken by the falling debris between us.

In that instant, I'd been so sure that we'd lost him. All I could do was cover my head, and pray that his helmet did its job too, until we could reach him afterwards. Having said that, judging by the strength and weight of the fall, that was only a possibility. Something landed on my foot, and I only felt the yell through my throat. I couldn't hear anything other than the falling rocks, and as something heavy knocked out the light on my helmet, I couldn't see anything either. This was terrifying. I could see nothing, hear nothing; I could only feel my own body as I curled up, small as I could, and waited for the falling to stop.

It was a few seconds after the last trickle stopped that I realized I could hear again. My breathing was loud and ragged, and came through in sharp breaths. My foot was in agony. Probably twisted. I'd moved it quickly enough away that it wasn't trapped, but I could hardly move it for the pain.

"Ben?" I called. My voice was cracked and rough. "Ben, can you hear me?" There was no answer. I hate split second decisions. The rocks could tip again at any moment, and I was afraid that if I tried to dig through to Benjamin, I'd just upset the rocks further and cause more damage. I decided to try to get back to the Mole, and from there I could consult the others, and find a safe way to dig to Ben without causing any more instability.

I felt around. The darkness was stifling. There was not a chink of light anywhere. The pathway had been greatly reduced to a winding, thin route through the piles of rocks. It was a miracle that there was a way through at all. As I moved on through, heaving myself up and down to squeeze through the narrow openings, I separated myself from the pain in my leg, as I had learnt to do from so many past experiences. The relief was great when I touched the smooth surface of the Mole, and briefly I understood how our rescuees felt when they saw a man in blue, there to get them out. The Mole was closer than I thought.

I only had to dig for fifteen minutes to find the opening. I rolled one final boulder to the side and pulled myself inside, my foot dragging uselessly behind me.

The others were frantic on the radio. We discussed the situation and came up with a plan. A good one. One that didn't involve me – I was received at the surface to be treated while two of my brothers went down in my place to get Benjamin.

Eventually they managed to get him out. He was unconscious, with blood down the side of his face and several broken ribs. They had no time to put him on a stretcher; instead, they got him in a fireman's carry and hauled him to the Mole. When I saw them from the bench I was on, clambering out of the Mole and carrying Ben between them, I couldn't help but wonder why he'd never heeded my warning to stay quiet. Surely it had been the vibrations from his voice that had sparked the second quake.

They handed him to a nearby paramedic, who treated him on the scene and settled him in an ambulance to take him to the hospital. That trip wouldn't have been needed if he'd just been quieter.

I couldn't help but feel bitter as the ambulance drove away. We do what we can to help people, but when they don't listen to instructions and get injured because of it, it still leaves the familiar, sour taste of guilt in us.

I was about to go and start packing away when a young woman approached me.

"You're the guy that got Ben out?"

"Yeah. He should be all right. Bruised ribs."

"Thank you so much. It must have been difficult."

"Yeah. Well, we got him out OK in the end. I think he might have been in shock, but the medics will see to that."

"Sorry if he was difficult. He hates the dark. When his vision's the only thing he's got, he can't stand it to be taken away."

"What?"

"Ben. Didn't he tell you? He's deaf."

After the rock fall, I had felt so isolated. I could neither see nor hear anything; I had to rely solely on touch to pull me through. If I had let my emotions take hold of me, I would have been terrified. Panicked. It's a lonely place inside your own body.

No wonder Benjamin was afraid of the dark.

At first I was angry at him for not telling me. But as I thought about it more, I reminisced about my own secrets that I tended to hide from people. There could be a subtle difference in the way people looked at you or spoke to you.

I guess Ben had experiences with people who treated him like he was simple. I know that most people with hearing-impairments are superb lip readers. I had a friend in high school who was nearly completely deaf. He didn't need you to slow down or talk loudly; he just needed you to look at him when you spoke to him.

This explained so much.

In an ideal world, Ben should have told me. But he was probably so used to trying to make people treat him equally that it didn't occur to him. And I should have asked him directly if there was something I should know about. Some people don't tell you things when they don't think they need to. In Ben's case, it was a crucial bit of information, but neither of us would have known it. How would Ben have guessed that I was the type of guy to talk over my shoulder?

And as I'm getting ready for bed, thinking over the rescue as I always do, I come to a conclusion. We've done so many rescues now that it's become routine: get the person, rescue the person, go for the next person. I mentally swear that next time, I'll go further than asking them their name. Because even asking for someone's name can become impersonal when done so many times. It's something I need to work on.

We heard on a post-rescue interview that Ben was out of hospital. He was the only casualty, having suffered two broken ribs and a dislocated jaw. This time we were lucky. There was a quick word from the woman I met after the rescue, and then thanks were expressed and the show had finished.

We learn from things like this. It's how we succeed. Someone once said, if you're not going forwards, you're going backwards. There's no standing still in this game. You've got to keep up, keep moving, expanding and growing. Learning. And it's an experience like today that makes that happen.

But dinner's ready, and my stomach's calling. I haven't eaten since breakfast, and a guy's got to look after himself. Next time I'll be ready. Today won't happen again.

Next time.