[Background info: This is based loosely on the truck heist gone wrong part of the episode (season 4, episode 2, a taste of panama city). It begins with the house arriving on scene. Severide is still a Lieutenant and in charge of Squad 3. Patterson is not in this story. Shay is still alive and a paramedic with Brett on 61 (not Chili). Dawson is also not in this story (I will explain more about why I didn't include her at the end of this chapter, but trying to include her character made it all a bit too complicated and hard to follow). It is loosely based on this scene; it starts off along the same lines and uses the accident they responded to but I changed parts to fit my version of the story better.]

Chapter 1:

'…Truck 81, Squad 3, Engine 51, Ambulance 61, Battalion 25… vehicle accident…'

As firehouse 51 got closer, they could see how bad the accident actually was. An armoured security van was in a very precarious position, as the only thing stopping it from falling from the bridge onto the concrete floor 100 feet below was the concrete barrier that was cracked and hanging off the edge, with a bit of metal straining to keep the barrier attached to the bridge. It was obvious that another vehicle had been involved in the crash, as something had hit the van side on, but apart from some debris, the other vehicle was no-where to be seen.

Chief Boden screeched to a halt, arriving on the scene first and assessing the situation as the rest of the house pulled up and got out of their rigs. Casey and Severide made their way over to their Chief, shouting orders to their crew and getting a good look at the van. Boden turned around to face his two Lieutenants, knowing they were waiting to see how he wanted to handle the situation.

'Right, we don't have a lot of time here, that truck could fall at any second. Casey, Severide, you two check to see how many victims we have inside. Get your teams to stabilise the vehicle, we need to buy ourselves as much time as possible, I have a feeling it's gonna go so let's move!'

Casey and Severide turned around and shouted orders at their crews.

'Cruz, Capp, Tony grab the chains and attach them to the van and to squad to stabilise the vehicle.'

Squad 3 ran back towards their rig, carrying out the orders given to them by their Lieutenant. Severide started to make his way towards the van. Casey was already there, and he shouted his instructions across to Severide and Truck.

'Truck, I need a ladder. Severide, there are two victims; one in the driver's seat and the other is in the back. I've got the one up front; you tackle the back.'

Herrmann and Otis were running towards the van with a ladder in hand. Severide nodded at Casey and ran towards the rear of the vehicle.

'Cruz, you finish shoring up the vehicle. Capp and Tony, I need you to get me the torch… we're gonna have to cut into the door.'

While everyone was rushing around the scene trying to gather the equipment they would need, Herrmann and Otis placed the ladder against the van and Casey climbed up. The van was almost on its side, leaning at an angle as he sat on the window and door of the truck and tried to assess how injured the victim was. He tried the door but it wouldn't open.

'Damn it, Otis get the K12.'

'Copy that Lieutenant.'

As Casey waited for Otis to come back, he glanced around the scene. A crowd had started to gather, watching the scene unfold before them. Casey sighed and was about to get Mouch to disperse the crowd when he saw two big guys pushing and shoving people out of the way to get to the front. He raised his eyebrows and looked towards Boden, who was helping squad pull their victim out of the rear of the van, them having managed to cut through the metal doors and manoeuvre their victim onto a backboard and to the nearest ambulance.

'Hey Chief, we got company.'

Boden turned around and Casey jerked his head in the direction of the newcomers. Boden swiftly made his way over, intending to disperse the crowd and hopefully get rid of these two men who seemed to have a particular interest in what was in the back of the now open van.

'Can you all take a step back please. Step back please. Thank you.'

The two men didn't move, still staring at the back of the van. Boden was relieved when he saw a police car approaching, the officers getting out and surveying the scene. Boden waved them over, just as the two men moved towards the van. Boden grabbed the hoodie of one of the men and shoved him to the ground. Severide had been watching the situation unfold and ran towards the other man, attempting to stop him getting to whatever was in the back of the van.

Casey, and the rest of truck had managed to get the door open and had lowered the driver from the van onto a stretcher. Their victim was being taken to the next available ambulance, with truck pushing the gurney. Casey was still on top of the van, and was about to move onto the ladder to get back down to the ground. He grabbed his halligan and just as he looked up he saw one of the men and Severide heading straight for the van. The guy slammed into the side of the vehicle, trying to pull himself into the rear of the van to get at what was inside. Before he could get any further though Severide had grabbed the back of his jumper and pulled him backwards, where he was handcuffed and taken away with his friend by the two police officers.

What nobody had realised was that the jolt to the van had dislodged one of the pieces of concrete that was holding it up, and while it had stayed in its position for a few seconds longer, it was now even closer to falling off the edge of the bridge. Casey had watched Severide apprehend the criminal from on top of the van, and was grinning at him. Casey had just opened his mouth to make some funny comment about the way Severide had handled the situation when the van jolted and Casey was thrown from his perch on top of the van and was left gripping onto the edge, hanging roughly 100 feet above a solid concrete floor.

Severide stood frozen. In reality it was less than half a second that these events unfolded before him, but to him everything seemed to go in slow motion. One moment he had been grinning at his friend and waiting for him to make a witty remark about how he had handled the situation, and the next there was a groaning sound and his best mate was thrown off the van and was left hanging onto the edge above a 100 foot drop. For a second he felt like he couldn't move as the horror of the situation dawned on him. But then he felt someone push past him and run at full speed towards the ladder, and he snapped back into reality and ran after that person. Severide shouted for someone to get another ladder as Boden started climbing the one already there, going as quickly as he could as they all heard Casey calling for help. Boden got to the top of the ladder and, whilst keeping his feet firmly planted on it to anchor himself, he reached forward and grabbed Casey's hand. He could see Casey's eyes, wide with fear as he tried to get some purchase on the slippery edge of the van, and heard his breathing becoming faster and heavier as he struggled to stay calm and hold on. Boden attempted to keep him calm while trying to get a better grip on him so he could pull him back up.

'I've gotcha, I've gotcha. Just hold on. Give me your arm, come on, give me your arm.'

By this point another ladder had been rested on the side of the van and Severide scrambled up. Herrmann grabbed his legs to keep him steady, as Otis and Mouch grabbed hold of Boden. Severide reached the top of the ladder, trying not to let the panic he felt at the sight of his best friend hanging off the edge of a huge drop distract him.

'Hold on bud. We're gonna pull you back up.'

Casey cried out with the effort of trying to hold on to the side of the van, and was struggling to get a purchase on the metal. Severide reached for Casey's arm, but just as he was about to grab hold of it the van jolted again. This new movement made the van tip even further on its side, resulting in the ladders sliding downwards, despite the firefighters best attempts to keep them steady. Boden and Severide dropped away from Casey, and they heard him yell as he lost the grip he did have on the van and they watched in horror as he disappeared from their view.

Severide stood staring at the place his friend's hand had been only seconds before. He couldn't draw his eyes away from the spot. Nobody moved, all horrified at what had just happened. One moment their Lieutenant had been sitting there, joking around with a smile on his face and the next he had fallen off the side of a bridge. Boden closed his eyes tight. This couldn't be real. They couldn't lose another one of their family. He knew he would have to be the first to look down and confirm what they already knew, but still, he gave himself a few more seconds before he attempted to compose himself and open his eyes. Boden got off of the ladder and walked around the van towards the edge of the bridge. Everything had gone extremely quiet, nobody making any noise as they tried to come to terms with what had just happened. Boden looked over and saw Severide still stood on the ladder. He cleared his throat and looked at Capp and Tony. They were also both in shock but understood and walked over to their Lieutenant to get him off of the ladder. Boden then took a deep breath and peered over the edge.

It was several hours later when they all arrived back at the firehouse. The rigs parked up but nobody got out of their vehicles. Everyone was still in shock, still in denial that the events that had taken place earlier that day had actually happened.

Boden rested his head on the steering wheel of his truck. He knew that as Chief he needed to say something to the rest of his team. But he was struggling himself. The image of his Truck Lieutenant was still fresh in his mind. A fresh wave of not only grief but guilt came over Boden, as he recalled the events that had taken place. He felt responsible. He was the one that had held Casey's arm, telling him he'd be alright, that they would pull him up. He was the one that had let go as the truck jolted once more. He was the one who hadn't managed to grab onto Casey before he had plummeted towards the ground. Boden hit his head against the steering wheel, trying to get these thoughts out of his mind. He could grieve when he got home. Now, he needed to be the Chief and that meant getting out of his vehicle. Boden took another deep breath before opening the door and getting out.

Otis, Herrmann, Mouch, and Jimmy were sat frozen in their seats. The ride back from the scene had been hard on all of them, as they tried their best to avoid looking at the empty seat of their Lieutenant. Otis killed the engine, only just realising he had left it running. He sighed heavily and stared out of his window, doing everything possible to not have to look at the empty seat beside him. Mouch and Herrmann sat facing towards the back of the truck, having refused to face forward and see Casey's empty seat. Jimmy had agreed to sit facing forward. He hadn't been at 51 for long, and while he had liked his Lieutenant and felt sad about what had happened he understood how much harder it was for the others, who had known Casey for a long time. Otis sighed again, before glancing to his right towards the empty seat. He teared up, wishing his Lieutenant was sat next to him, criticising his parking and making jokes about letting the candidate drive the truck instead.

Boden slamming his door seemed to bring everyone to their senses. The sound of other doors opening and closing broke the silence, but no-one spoke as they slowly began to take off their turnout gear. Severide was the last one to get out, slowly jumping down from squad in a trance like state. He had been like this since Casey had lost his grip on the truck and fell. He didn't want to believe it had happened. He wanted to walk around the vehicle, and see Casey hanging his turnout coat on the truck door, before ruffling his hair and grinning as he made his way over. Severide, like Boden, felt guilty about what had happened, he blamed himself for the events that had unfolded. He should have gotten to the criminal sooner, before he had bumped into the truck and made it more unstable, causing it to jolt and send Casey over the edge. He shouldn't have frozen when he saw Casey fall over the edge and cling onto the truck. He should have been quicker to get up that ladder and grab Casey before he lost his grip and fell. But now he was gone, and nothing was going to bring his best friend back.

Herrmann had gotten out of the truck, relieved that he didn't have to risk looking at the empty seat any-more. He took his turnout jacket off and turned around to hang it on his door, and that's when he saw them. Casey's boots were on the floor next to the front door, one led on its side, and one stood up straight. Herrmann froze, staring at the boots, as he welled up at the sight of them. He thought back to when Casey was a candidate on truck 81. He'd got into trouble with his Lieutenant several times for slowing them all down when gearing up for a call, because he liked to make sure his boots were placed next to each other, standing up so as not to make a mess. It had taken a chat with Boden to finally make the young candidate realise that when responding to a call, it was okay for him to leave his things in a mess, as he could tidy it all up when he got back. Still, everyone knew that this bothered Casey, and even though he didn't straighten up his boots before a call anymore, they knew that as soon as he got back from a call the first thing he did was stand them up. Herrmann rubbed his face and his eyes, trying to pull himself together as he walked over to the boots and stood them up, arranging them in the way he knew Casey had liked. He stepped back, nodding to himself before turning around and walking away from the truck.

Everyone started walking towards the common room, and stopped as they reached it, just inside the entrance. The room was as they had left it, chairs pushed away from the table, magazines, books, and laptops left scattered across it. And at the head of the table, was a half-finished mug of coffee and a newspaper, left open on the puzzles section, a crossword in the process of being filled out. They all stood frozen by the door, staring at where Casey had been sat only hours before, laughing and joking around with the rest of his crew as they waited for Jimmy to finish making lunch. They stayed like this for a moment before Boden broke the silence. He cleared his throat and glanced around at his team.

'Um… okay… I have taken the house out of service for the rest of shift. I want everyone in the briefing room in 5 minutes.'

Boden turned around and headed to his office. He knew he had to try and compose himself before talking to everyone else, but this was easier said than done. All he wanted to do was lock himself in his office and break down, but he knew that this was not expected of a Chief, and knew this was not how Casey would want him to react. He sighed again and sat behind his desk placing his head in his hands as he tried to figure out what he was going to say to everyone. After a couple of minutes, he looked down and stared at the floor. Just as he was about to stand up to go to the briefing room, he looked at the drawer on his desk and remembered something Casey had given him years ago. He opened the drawer and rummaged through it, finally finding what he was looking for. He pulled out a box, full of envelopes with people's names on them. He set the box down before sitting behind his desk once more and rubbing his face as he thought back to the day Casey had given it to him.

There was a knock at his door. Boden looked up and saw Casey standing outside his office. He waved him in and Casey entered, shutting the door behind him before turning around to face his Chief. Boden saw he was holding a box in his hands, and looked at him questioningly.

'…So… what's in the box Casey?'

Casey took a moment to respond, looking at the box in his hands before handing it over to Boden.

'Letters. You know… just in case…'

Boden knew exactly what he meant, and frowned as he stared at his young Lieutenant.

'What brought this on?'

Casey stared down at his feet, and sighed before answering Boden's question.

'Umm… well… remember that call from a few months ago. The highway pile up. Well, the amount of DOA's that day got me thinking. Tomorrow is not guaranteed for anybody… those people had never expected to be in a crash. They expected to get on with their days, before returning home to their families, friends, loved ones. They never got a chance to say a proper goodbye as they never saw it coming. And so, especially with the job we do, there is no guarantee that we'll come back after every call. So I wanted to have something for everyone… to try and… well… in case one day I don't… so yeah. Sorry, it seems so dark and stupid thinking about it now but I've been working on it for a while… you don't have to take it if you don't want, I can keep it in my office or something… It's just this is important to me and I wanted someone to have it who will remember about it… just in case.'

Boden stared at Casey, and then at the box in his hands. All of the envelopes seemed to be fairly thick… no wonder it had taken him this long to write them. Boden nodded his head as he looked back up at his Lieutenant.

'Yeah, of course. I'll put it in my drawer. Although I really hope I never have to get it out for that reason.'

Casey smiled at Boden, before turning around and walking out of the office. Boden watched him walk off, before opening one of his drawers and placing the box towards the back and closing it again.

Thinking of that day all those years ago brought tears to Boden's eyes, as he realised what giving out these letters meant; Casey was actually gone. He would no longer come to his office, filling him in on what was going on with his truck company, complaining about some prank Otis had played. He would no longer go on fishing trips with him and Severide. He would never sit at Molly's, laughing with his firehouse family about a weird call they had responded to that day. Boden cleared his throat. He couldn't be in this state when he spoke to everyone else. He glanced down at the box again, seeing one envelope resting on top of the rest. It had Jimmy's name on it, and he remembered every time Casey had come into his office with a new letter to add to his box. Jimmy had been at 51 for a few months now, and Boden knew he saw potential in his young candidate, which was why he was not at all surprised when Casey had walked into his office a few weeks back, carrying the envelope and setting it on Boden's desk before smiling and walking back out. He took yet another deep breath before grabbing the box and heading out of his office and towards the briefing room.

Boden stood just outside of the conference room, staring at the doors in front of him. He knew that he had to go in and talk to the others, but he couldn't bring himself to walk into that room. This was wrong. He was going to be walking into a room that was one person short. There was going to be a gap where Casey always stood, leant against the wall casually and grinning as he spoke to Severide. It was this thought that snapped Boden back into action. The others were suffering just as much as he was. Now was not the time to grieve. He had to be a leader for his men, and that meant walking into that room and being there for them. Boden took a deep breath, looked down at the box in his hands and walked through the doors. As he walked into the room, everyone looked up from where they had been staring down, tears in their eyes. Boden cleared his throat and glanced around the room. He took another breath before he spoke to them.

'So… I want you all to know that the Chaplain is going to come over, and is there for you to speak with. It is not mandatory but I recommend that you do. I, um… this is hard… for everyone… It is always hard to lose someone and losing Casey… it is unimaginable. But here we are. He was… is our brother… our friend… and I am sure he is looking down on us from up there…'

Boden paused and looked around the room. His eyes passed over where Casey usually stood, and he did a double take as he thought he saw a figure stood in that position. When he stared at the spot though, there was nobody there. Boden shook his head slightly, of course there was nobody there, Casey was gone. He looked down at the box in his hands before he continued.

'A few years back, Casey came into my office… with this box. We had a bad call, a few months previously and he… well, he told me that tomorrow is not guaranteed for anybody. He, um… he said he wanted something that would say goodbye if he couldn't, if the unexpected happened. I never wanted to see this box again. Ever. But I agreed to keep it safe for him. It was at the back of my drawers, and… well. Every so often he would walk into my office, with a new letter. He wouldn't say anything, he would just walk in, grinning widely and place it on my desk before walking out again. I promised him I would be the one to give these out if… and so… here you go. Open them whenever you feel ready. If you want someone there with you, you just have to ask. I'm gonna give these out, then you're free to go.'

Boden finally looked up, to see everyone staring at the box in his hands with tears in their eyes. He gave the letters out one by one, and waited until everyone had walked out of the room. He looked back into the box, where there were a few remaining. He looked at the names on the envelopes, seeing one for his sister and his niece as well as a few for people who were no longer working at 51 that he would need to post. Finally, he pulled his own out and stared at the writing on the front of the letter. He suddenly felt the need to get somewhere out of sight, and so started to make his way towards his office. He had just walked past Connie and reached his office doorway when he remembered seeing her name on one of the envelopes. Of course Casey would write something for his Chief's secretary. That was the kind of person he was. He stopped, collected himself and turned back around to face her.

'Uh Connie.'

Connie turned and smiled sadly. He noticed her eyes were slightly red, which he was slightly surprised at. Connie never showed her emotions. And while Casey was a very popular and very well liked man, he hadn't thought that she was that close with Casey.

'Yes Chief.'

Boden picked out her letter and held it out to her.

'Casey… he wrote these and there is one for you. I told him if he… I said I'd hand them out.'

Connie nodded slightly and took the letter. She stared at it and when she looked back up, Boden was once again slightly surprised to see her eyes were teary.

'He, uh… would he have… would it have been… actually don't worry. Thanks Chief.'

Boden frowned slightly, and nodded. He had almost made it back into his office before he realised what Connie had wanted to ask. She wasn't there, she hadn't known it had happened until they all got back. He breathed deeply before he turned back to face her.

'No. From that height… it would have been instant…'

Connie nodded at him, and he shut the door to his office and drew the blinds swiftly before he collapsed against the wall and slid down so he was sat on the floor. He stared at the letter in his hands and finally allowed himself to break down.

[So firstly, please don't hate me for killing Casey off so quickly! I'm sorry! Secondly, I feel like I can explain why I didn't include Dawson in this story now. When I started writing the story, my original idea was to include her but for Casey to just be badly injured, and I was going to use her line earlier in the episode 'keep your badge off the wall' to foreshadow this accident and injury. However I couldn't figure out how he could survive a fall like that. So then I thought maybe I could write a different story, this one, instead exploring the grief felt by the others at 51 and how his death would affect them. So I didn't include Dawson because I felt like the story would have then just revolved around her grief and I wanted to write a story showing how everyone at 51 would be affected by Casey's death. However just because Casey is dead, which I apologise for now, this first chapter was really hard to write, (it was supposed to be a cliff-hanger but that felt cruel) that doesn't mean he isn't in the rest of the story… and I'm not just talking about him being mentioned in the letters he wrote… I'll give you a clue, was it just Boden's imagination that meant he saw a figure in the briefing room… or was it something else…!]