Casey dropped like a stone but somehow I managed to get behind him and we fell together behind the filing cabinets. Another shot pinged off the metal. Herrmann was to my right, having dived behind a stack of desks. His legs were exposed and I saw the impact of a bullet in the paper right next to him. It was like I was watching television. It felt that unreal. Then I looked down at Matt and everything crashed down on me.

There was nothing I could do for him. In full kit, I couldn't find where he'd been hit. I yanked off my mask and my gloves and started feeling his chest for blood. I wasn't aware of Herrmann shouting into his radio, nor of the men still crouched by the door, arguing now instead of shooting at us. Casey fumbled for my hand, stopping it.

'I love you,' I blurted, not thinking. I was in shock, I knew. I felt numb. The only thing going through my head was I love you I love you I love you. Suddenly, Herrmann was beside us, pulling me upwards.

'Get him up!' He yanked at Casey's arm, hauling him upright. 'There. That door.' Herrmann nodded to the door behind us and we made for it, trying to keep low but in reality, just stumbling blindly, expecting to feel bullets hit my back at any moment. I lashed out with my foot at the cooking apparatus as we passed it. It toppled, the kit sliding off and smashing into the fire, which ignited with enough force to send us stumbling backwards. Then we were at the door and through it. Herrmann turned instantly and pulled a set of desks across the door.

'Severide,' he gasped, 'came up the stairs, distracted them.' No doubt Severide and the others had charged to our rescue. 'We need to get out of here. Oh shit,' he lurched forwards. Casey had suddenly wilted next to me and I couldn't hold his full weight. Herrmann helped me lower him to the ground. This time, training kicked in and I pulled open his jacket and found where he'd been hit, on the right of his chest. As long as I didn't look at his face, he was just another person needing treatment. I reached around his back, feeling for an exit wound, and I nearly lost it then, being so close to him, smelling his scent. There wasn't an exit wound, which was a good and bad thing. As long as he was breathing ok, which he was, and he was conscious, which he was, and wasn't losing too much blood, we had time to get him out of there. We were in an open corridor and there was nothing I could use to stop the bleeding, so I ended up using his t-shirt, ripping off the bottom half and wadding it up.

'You undressing me, Gabby?' He mumbled and that was enough to push me over the edge and for a moment, I couldn't see for the tears. Herrmann gave my shoulder a squeeze.

'C'mon,' he reminded me, 'we still gotta get out of here.' I'd been dimly aware of our radios going this whole time, but seeing as I had a one-track mind that started and ended with Casey, I didn't have a clue what was going on.

'How? What's going on?' I asked, as I pulled off Casey's belt to hold the dressing in place.

'Chicago PD are outside but there's more than just those two guys. They reckon there's six or seven of the bastards. Some of them have got PD in a gunfight outside. Severide and Otis had to go up to escape but they got separated, Severide's on the eight or ninth floor, Otis is in some broom cupboard. We've got to find our own way out.' Both of us looked at the smoke now billowing from underneath the door. 'Fast.'

I pulled my mask on, amazed at how training had abruptly overridden my panic and concern. I didn't particularly want to put Matt's mask on, because it meant I wouldn't be able to see his face and judge how he was doing. He breath was coming in shorter and shorter gasps and he was sweating buckets.

'Matt, baby,' I put my hands either side of his face. There was no danger of tears now. He needed me. 'Calm down, ok? You're going into shock, you just need to focus and stay with me.' His blue eyes found mine. 'You can breath, you just need to calm down.' He nodded and took a deep breath, groaning as he exhaled. Herrmann was on the radio to Boden and Severide. I heard their voices without really processing them.

'There's another stairwell,' Herrmann said. 'Severide and Otis are coming down it to help, we gotta head that way.' Together, we stood up. Casey waved me off.

'Am ok,' he gasped, gripping Herrmann's shoulder. The corridor was deserted but for old cardboard boxes and office debris like seat cushions and keyboards. It made it easier going but we were totally exposed.

Once we got to the next stairwell, it was clear that something was wrong – everything was too still. I could just about hear muffled footsteps and voices, but everything echoed and it was impossible to tell who or where they were.

'Stay here,' Herrmann said, passing Casey over to me like he was a hose, just drooping him over my shoulder, and he crept towards the stairs. 'I'm going to check it's clear below us.'

'Herrmann, no,' Casey and I said together. We both took a step forwards, which is when I realised that I had to let Herrmann go and check it out, because the two of us were a clumsy tangle of limbs. I pulled Casey back against the wall and he didn't resist, probably realising the same thing. 'We're going to be ok,' I told him. 'So's Herrmann. Just stay there.' I unwound his arm from my shoulder, reassuring him that I wasn't going anywhere. I know he was concerned for me, but there was a glimmer of fear in his eyes that made me feel like I was leaving a fearful child in a darkened room. I'd never seen him look like that, and it made me ferociously protective.

'Herrmann,' I hissed, peering over the stairwell, down to the flights below.

'Dawson?' The voice came from above me and I looked up to see Severide, two or three flights above.

'Severide?' Herrmann stuck his head out from below us. 'Hi guys.' There was something comic about the scene and I felt a wave of relief wash over me. Then a fourth head appeared, just below Herrmann, one that wasn't a friendly face: black hatted, bearded and gaunt.

'Herrmann, run!' I shouted, as the man disappeared. Then Herrmann was gone too, and there were shouts below us, gunfire, more shouts. Casey appeared next to me, shouting for Herrmann. Then we heard the unmistakable sound of footsteps on the stairs.

I grabbed Casey and began hauling him up the stairs, hyperaware of the footsteps bearing down on us, of our own clumsy progress. I'd completely forgotten about Severide until he appeared beside us, practically picking up Matt and throwing him across his shoulders, then set off up the stairs two by two. Then we were charging back across a corridor identical to the one below and burst through into an office. I glanced back into the corridor as someone appeared at the other end. I leapt backwards as the window in the door exploded as a bullet hit it, and then we were flying through the office. I could barely keep up with Severide. Then we were through to another stairwell, and I'd completely lost my bearings in this stupid, godforsaken building, and up the stairs we went again.

'Severide, stop! We've got to hide. We can't outrun them!' But Severide didn't seem to hear me, he just kept going, carrying Matt over his shoulders. 'Severide,' I pleaded. They could be anywhere. Finally, on maybe the tenth or eleventh floor, Severide slowed and I yanked him out of the stairwell, back into the corridor. There were a line of doors and I led us into the third one, into something like a photocopying room. There was no way out.

'Shit,' I gasped, helping Severide with Casey, who was completely unresponsive. I felt his pulse, listened to his chest. There wasn't too much blood and his pulse was strong. It must've been the pain, I thought numbly. Passed out cold.

Severide still hadn't said anything. He was slumped next Casey, panting like a horse, chest heaving and eyes practically rolling in his skull. It'd been a superhuman effort to carry someone like that, and only Severide could've done it. I felt his pulse, suddenly fearful that his heart would give out. It was pounding, but stable.

Herrmann, I thought, with a useless glance to the door as if I could help. Please be ok. Casey groaned and I took his hand to let him know I was there, and kissed his forehead without thinking.

And then, as if it couldn't get any worse, like I wasn't desperate to be anywhere else but here, I realised I could smell smoke.

Hi all, thanks for reading! Hope you enjoyed chapter 2. I was debating for ages whether to make this a short one or a long one and am still undecided. Probably a medium one! Also you might realise that my stories are quite dark… My plan is to kill someone off before the end of this story. Potential victims are Casey, Dawson, Herrmann or Severide because they're my favourite characters… Anyone want to pick?

Oiaso, TildaJoy, Peyt fan 4ever and Sarah - thanks for your reviews. Sarah, your message made me laugh out loud and completely got me motivated to carry on with this, so thanks!

Ciao x