This is a rework of season 4 episode 13 "The Sky is Falling". What happens if Casey jumps in to save the day? Hope you enjoy!

Casey's heart thundered in his chest, blood roaring in his ears, blocking out the sounds of the outside world around him. He had just been about to open the basement's electrical panel when the rapid-fire shots rang out, echoing off the empty walls.

The shots increased in tempo and Casey clutched his radio, eyes wide as he scanned his surroundings.

"Mayday, Mayday!" Otis' voice crackled over the radio. "We have an active shooter. Need rescue!"

Frozen in shock, Casey's mind reeled as he tried to figure out what he could do to get his team out alive. They were scattered around the building and there was no telling how many shooters there were.

He jumped as his radio came to life once more, Chief's gruff tone panicked. "We have an outside shooter. Hold your positions until further notice!"

Picking his halligan off the ground, Casey grabbed his radio once more. There was no way he was going to stay put. He was in charge of his team. He needed to make sure they were safe.

"81, do you copy?"

Silence answered him. He was about to send a call to 61, but another round of rapid firing cut him off. It was louder this time, meaning the shooter was getting closer to him and potentially his team.

Casey switched his radio off so it wouldn't give away his location and crept to the edge of the wall where the opening to the hallway was. He grabbed his helmet, holding it to his side so he could get flush with the wall, leaning slightly outside its safety to take a peek down the hallway.

A guy dressed in all black, a large gun in his hands, was walking down the hallway, pausing every so often to shoot at something he saw in the many rooms that lined the hall. Casey ducked each time, body jerking with each reverberation as the lieutenant heard people scream out before falling silent. He needed to do something and he needed to do it fast.

The shooter ducked into a door just down the hall, giving him an opening. Casey was just about to move when he heard soft thunks down the metal staircase to his left. He paused, lowering himself as he raised his halligan, ready to swing at whoever came around the corner. Before the figure could fully descend the stairs, Casey had to duck back as the shooter reappeared, having heard the noise.

Almost immediately the guy began shooting again, sending a spray of bullets toward the staircase without thought. Casey heard the steps retreat back up the stairs. There had been no shouts of pain, so the person, whoever it was, hadn't been hurt.

They weren't in the clear, however, as the shooter started forward, ready to follow the person up the stairs and finish what they started. Casey couldn't let that happen. It could have been one of his team and there could be more hiding up there. No. This ended here.

"Hey!" Casey shouted, not really thinking his plan through as he got the shooter's attention. The man swung toward him, a brief look of surprise crossing his face before it morphed into a twisted smile. Then he started shooting.

Casey dove blindly, crashing into a pile of boxes stored on the side of the electrical room. Before he even stopped sliding, he used his momentum to carry him forward, kicking with his legs so he slid behind a workbench. With only seconds before the shooter found him, he needed to come up with a plan to escape.

His head whipped around violently as he scoured the area for anything he could use. There wasn't anything around. He cursed inwardly as the shooter entered the room, his heavy boots kicking the boxes Casey had just crashed through. He was almost right on him.

Doing the only thing that popped into his mind, Casey pulled off a boot and crawled forward as silently as he could. He rounded the workbench and froze as he saw the shooter's back. The man was at the far end of the table, his gaze focused in the opposite direction. Casey used this to his advantage, tracking the man's movements as he laid his boot so the heel was facing up and it stuck out from behind the bench, making it look as if he was on his hands and knees.

The shooter turned and Casey moved, crawling to the other side of the work bench as the man rounded the table where Casey had been first hiding.

There was a moment of pause before the shooter said, "Ha! I got you now. You're dead, fireman." He jumped forward, toward the boot Casey had placed, and began firing wildly. There was no thought to this man's actions. He was out for blood, plain and simple.

Using the brief distraction as cover, Casey stood and rounded the table so he was directly behind the shooter. He must have heard Casey as he started to turn. Without a moment to spare, Casey brought his arms up and cracked the man on the head with his halligan. The metal met the man's soft flesh with a sickening crack and he crumpled. The shooter's finger was still on the trigger as he fell, his body turning with his previous momentum and bullets sprayed. Casey crashed to the floor as dove once again, his halligan falling from his grip as he brought his arms up to shield his face. It was over in a second, the basement eerily quiet after so many shots had been echoing off the walls. It was in this quiet moment that the pain registered. Casey grabbed his leg, clutching his thigh as hot white pain rushed through him, blood pouring through a hole in his turnout pants. He had been shot and now he was stuck as the other active shooters still roamed the building.

Hands slick with his own blood, Casey scooted backwards until he connected with the far wall, five feet from where he had been shot and ten from the downed shooter. He left a trail of blood in his wake and his stomach clenched. That wasn't good. Gunshots bled a lot of course, but this was too much. The bullet must have hit an artery. If he didn't get out of here soon, he was going to bleed out.

A few more shots rang out in the building, but the sound was faint. The shooter must be on the top floor of the building. The one Casey had taken out must have been the only one on the bottom floor with him. Feeling that it was as safe as it could be, Casey reached up and grabbed his radio's switch. It took a few tries to twist the knob, his fingers slippery with blood, and he groaned in relief when he heard the radio's familiar chime.

He took a moment to make sure that the radio's volume was on low before he pressed the talk button.

"Chief, this is Casey. I'm trapped in the basement, not sure where the rest of 81 is." He released the button and pressed his head against the wall as he clutched his thigh with his left hand. Blood was still pouring from the wound.

"Chief," A voice said, and relief poured through Casey as he realized it was Otis. "I'm with the rest of 81. We're in a secure spot with some civilians. BC corner. I tried to reach Casey but the shooter saw and open-fired. I'm fine, but there were a hell of a lot of shots down there."

"Otis, thank god. Casey, report your status."

Casey opened his eyes. Huh. When had he closed them? He reached for his radio with shaking fingers. "I got hit in the leg. S'blood everywhere." He frowned at his slurred speech. Everything was beginning to become numb and a chill had set in even under his thick turnout gear.

"Chief, this is Dawson. It sounds like the bullet hit his femoral artery. He could bleed out if he doesn't get out of here fast. We're going to have to go radio silent, but I'll talk him through making a tourniquet to buy him some time"

"Hang tight," Boden replied, worry evident in his voice but still emanating his Chief-trained calmness on them. "SWAT is on the way."

His line went dead and then 81's direct line crackled to life.

"Matt, we need to do this quickly; we can't talk long. You need to tie a tourniquet above the wound to try and slow the bleeding. Grab whatever you can and tie it as tightly as possible okay?"

Casey nodded and it took him a moment to realize that she couldn't see him.

"Kay," he slurred as he looked around, bleary eyes hardly focusing on his surroundings. Somehow he managed to spot a loose cable that had coiled on the floor. With effort, he leaned to his right but stopped as his leg screamed in agony. He panted as what felt like lava shot through his leg, the pain making his toes tingle. It took a moment of deep breathing until he was able to move again, snatching the cable and sitting back upright where he slouched against the wall, sweat dripping down his face as he breathed hard. Before his strength failed completely, he pulled the cable under his leg, above the wound, and wrapped it tightly. He grit his teeth as he pulled hard, ensuring there was enough pressure before he tied the cable off. Casey watched as the blood flow slowed. The tourniquet had worked.

"Done," he panted into the radio, exhausted.

"Great job Matt. Now I need you to keep pressure on that until we can get you out of here, okay?"

"Copy," he said before turning his radio back to silent. Now it was just him, alone, bleeding in this basement as he waited for SWAT to rescue them.

A loud bang resonated from somewhere inside the building and Casey jerked, crying out as his left leg screamed in agony. His breath came in short pants as he gripped above the wound, desperately trying to get the pain to stop.

It took a few moments of slow breaths, but eventually the pain died down to an intense throb and Casey was able to think again. He must have fallen asleep- or passed out most likely- from the blood loss. He wasn't sure how much time had passed, but it was clear that the shooters were still in the building.

He took a moment to listen to his surroundings and found that his floor was still clear. Making the executive decision, Casey reached down and switched his radio back on, volume still on low. If he didn't get out of here soon he could bleed out so he might as well use the radio to try and save his life.

"Chief…" he said and coughed, his voice hoarse and throat extremely dry. He also found the effort to talk hard, as if his lips didn't want to move. "S'Casey. N'd h'lp."

His plea hung in the air for a moment before Boden's voice rang through the line. "Shooters are still active in the basement, Casey, we can't make it down there. How bad is it?"

His eyes roamed sluggishly over the puddle of blood encasing his left leg. "Bad."

Boden cursed over the line and Casey knew he was desperately trying to figure out how to get to him. The lieutenant didn't ever admit things were bad, so to do it now spoke volumes on his current state.

"Chief!" Severide's voice cut in, "me and Cruz got the victim out of the window. I have access to the building. Send me in alone. I'll make my way to him and do what I can until SWAT can get in."

"I don't like it."

"Casey's in bad shape. I can help him! Just let me go in."

The radio crackled for a moment before Boden replied, "Okay, but be careful. One sign of trouble and you get out of there, you hear me?"

"Copy Chief."

Casey reached down with numb fingers and turned his radio off once more. He was only vaguely aware as his heat tilted back, resting against the wall as his body went lax. Everything was pleasantly numb and Severide was coming. He would be okay.

"-ase. Casey!" The gruff voice along with a rough shake of his shoulders roused Casey, his eyes cracking open as his blurry surroundings came into view. There was a shape in front of him. It took a couple of blinks to clear his vision, but eventually the shape took form and Severide came into view. He was kneeling on Casey's right side, away from the puddle of blood, and his face was close to the lieutenants as he examined Casey's condition.

"Sev?" He slurred, tilting his head to get a better look.

"Yeah, it's me bud. I'm going to help you out. You're in rough shape."

Casey frowned. His leg didn't even hurt anymore, how bad could it be?

"S'not painful."

Severide's ice blue eyes roamed over his face, his brows creased in concern.

"You're going into shock. You've lost too much blood. The bullet hit an artery. I need you to stay awake for me, okay?" He said as he gently patted Casey's face. "No sleeping on the job."

Casey blinked his eyes open in surprise. How did his eyes keep closing without him realizing?

In one fluid motion, Severide unzipped his jacket and slid it off before reaching over and draping it over Casey's front, tucking in the edges so it would stay in place. Then he shifted so he could better see the wound, hissing when he got his first close look. His fingers skimmed over the tourniquet and then he pulled the cable, tightening it further. This elicited a reaction from Casey as the wound shot pain through his leg. It was duller than it had been, but still there.

"Sorry," Severide said as Casey groaned, shifting uncomfortably on the wall. "I know you're not supposed to keep this too tight for too long, but the wound is still bleeding a bit and you can't afford to lose any more blood."

With a lot of effort, Casey managed to meet Severide's eyes. "S'kay."

"I'm going to get you out of here, Case. You're not dying on me today."

If Casey had the energy to smile he would have. Instead, he just kept eye contact with Severide trying to let him know he trusted him with his life completely.

Severide returned the stare for a moment before he reached down and switched his radio on.

"Chief, I found Casey. He's even worse off than he thought. SWAT needs to get in here now. We'll need a backboard and an IV brought down here as soon as it's clear."

"Copy. SWAT is gearing up to go in now. Hold on until help arrives."

"You're going to be okay, Case. Just hold on a bit longer."

Casey tried his best, but his body was so exhausted his eyes slipped shut, his mind wandering between awake and darkness. He heard snippets of noise, loud bangs, doors splintering, shouts, and he could feel Severide next to him, one hand on his leg to stem the flow of blood and the other gripping his lifeless hand. He heard when things changed, too. The loud noises quieted before Severide shouted out, "Here! We're in here!"

The blackness took over again and then he was being moved, his body lowered and rolled before something hard was slid behind his back.

"-Casey. Hang on!" Severide. He was still here.

A sharp scratch barely registered in his arm and then he was moving.

"-ive blood loss… Med…"

And then the darkness swallowed him completely, leaving him floating in pain-free bliss.

He came to slowly, his body rebooting in sections. At first there was nothing, just a general sense of floating, his mind without a body, but gradually things started to form around him as the soft sensation of a blanket on his skin prickled through as well as the cold air flowing freely into his nose, tickling his top lip. He pulled toward these sensations and felt himself slide back into the present. There was a fluffy pillow behind his head and a soft beeping filled the air. It was confusing- where was he? Why did his body feel numb? He racked his brain for a moment and shot upright, eyes popping open as his system flooded with adrenaline. The shooter. Where was the shooter? Was his team okay? Was Sev-?"

"Easy, easy, Case," A voice soothed, gentle hands pushing him back against the bed. Casey turned his head and saw Severide standing next to him, an empty chair behind him where he had presumably been sitting before Casey had woken up.

"Everything's okay," Severide reassured. "You're safe."

"Everyone okay?" He rasped and winced, his throat gritty like sandpaper.

Severide reached over and grabbed a cup of water, a straw already in it, and held it up to Casey's mouth. The lieutenant drank greedily, sighing when the cool water soothed his aching throat.

"Everyone's okay," Severide said as he set the cup down. "You were the only one hurt. What were you thinking going after a guy with a gun like that? You could have died. Hell, you almost did!"

Severide ran a hand through his hair and Casey saw how worried the other lieutenant had been. His clothes were wrinkled and there were shadows under his eyes.

"How bad?" He asked quietly.

Severide looked at him for a moment before he turned and pulled his chair so it was next to the bed. He sat in it heavily, leaning back as he crossed his arms over his chest, his tired eyes roaming over Casey's face.

"Bad enough. The bullet hit your femoral artery and was lodged there, rubbing against the bone. Every time you moved, even a little, it shifted the bullet making it bleed even more. The tourniquet saved your life, but you lost a lot of blood. When I got to the basement and saw you up against the wall, the pool of blood under your leg…" He tilted his head back and rubbed his hands over his face. "Man, I thought you were dead. You scared the shit out of me- out of all of us. The rest of 51 is in the waiting room right now."

Casey bit his lip and eyed Severide guilty. He hadn't meant for any of this to happen. He never wanted to cause any of them pain.

"I'm sorry."

The lieutenant's head snapped down to look at him. "What are you sorry for? You saved your team. What you did was brave as hell. Just don't make it a pattern. My back can't handle sitting in these chairs for so long."

Casey chuckled and felt the tension in his chest release. His team had his back, they were all family, and they always would be.

"How long was I out?"

"About 7 hours. You were rushed into surgery and were in the OR for two and then you were out for an additional five. Your body needed the rest after the trauma you went through. You lost almost 40% of your blood volume."

Casey nodded, trying to process this information. "What's my recovery time?"

Severide gave him a knowing look as he smirked. "Just woke up from major surgery to remove a bullet in your leg and you're already jumping to go back to work, huh?"

Casey smiled sheepishly. "Nothing beats being a firefighter."

Severide's smile softened. "Agreed. Doctors are hopeful for a full recovery after a couple of months. In 6 weeks you'll start physical therapy and they'll go from there. But don't worry, you'll be crawling hallways again in no time. And know that all of us at 51 are here for you, don't forget that."

A tear ran down Casey's face as his tired brain processed everything that had happened. He brushed it away, a smile on his face. He was so damn lucky to have such supportive friends.

Severide clapped a hand on his shoulder and stood. "Now, you ready for some visitors? There's some anxious people out there waiting to see your ugly face."

Casey rolled his eyes. "Bring them in."

Casey couldn't help but smile as the 51 crew squeezed into the room. Each of them had a relieved smile on their face, but he could see how much stress his injury had caused them.

"I just wanted to thank all of you," Casey started as Boden walked into the room, the last person of the group to enter. "You guys stayed calm under an extreme circumstance and worked together to not only save your lives, but the lives of the civilians in the building as well. I know not everyone made it, but you guys did damn good work and I'm proud of you."

The group stared at him silently and Casey shrunk back an inch. He looked over at Severide in panic. What had he said wrong? But Severide only rolled his eyes gently, a grin on his face.

"Leave it to the lieutenant to almost die and the first thing he says after waking up from surgery is giving us a thanks," Herrmann said and the group laughed.

Dawson sniffed and wiped a tear that had escaped, though a smile still graced her lips. "Don't ever play the hero again, Matt. You stick to firefighting, not policing you hear me? Leave the taking down the bad guys for the CPD."

Casey chuckled and rubbed the back of his neck, heat rising in his face. "I guess I didn't think that one all the way through," he admitted, earning another chuckle from the group.

"It's why we love you, lieutenant," Joe said and everyone nodded in agreement.

"You did good in there, Casey," Boden said as he stepped forward, resting a hand on Casey's blanketed leg.

"Thanks Chief."

There was a moment of pause and then Herrmann said, "Okay, enough with the sappy stuff. You think they're serving pudding in the cafeteria?"

"I could go for some pudding," Mouch piped up and Otis nodded his head rapidly in agreement.

"Now that we know Casey's okay, I'm starving."

The group started bickering back and forth, Capp insisting that the pudding was for hospital patients only while Mouch and Otis argued back, the rest of 51 joining in on the antics. Casey just sat back and smiled, watching his family in front of him. As he looked around at everyone, he couldn't help but feel grateful for all he had and the amount of support that radiated through the room. He would be okay and his family would be there every step of the way.