Chicago. One of the most dangerous cities in the United States. In this city, firefighters, policemen and doctors have taken an oath to protect the people in their daily lives, while dealing with the violence and fear that hangs over them. It is in this context that a firefighter cadet, a medical student and a patrol officer try to find their place in the midst of a dangerous city, and at the same time try to help people and live their days as normal people. These are their stories.

In a building on fire, a man appears running with firemen's equipment, trying to help a woman save herself. In the meantime, three firemen appear, trying to help the other save the woman.

"They say that those who aspire to be firefighters go through a baptism of fire to prove themselves worthy of fighting city fires."

-Casey! How much time do we have?

The firefighter was facing Brigade 51 Captain Matt Casey, who was accompanied by firefighters Otis, Herrmann and Mouch.

(Casey) - I can't tell. Why did you come back?

-I heard a woman screaming and decided to go back to save her.

(Herrmann) - Brave, kid. But remember the risks you are taking by doing this.

-I know.

The firefighters start running down the stairs, down the building, which begins to collapse.

"That's a risk that firefighters take every day. Never have the challenges been greater. But that, it's out of the desire to want to save people."

Chicago Med...

A pile of patients arrived, some with burns, others in serious condition.

"Being a doctor is a challenging thing. A split second determines who lives and who dies in the world of medicine. Sometimes a simple mistake can lead to an even greater consequence in our lives."

-One more?

The man was talking to Connor Rhodes, one of the best neurosurgeons in Chicago.

(Connor) - We already have one more victim of that fire. The pile of patients just keeps coming.

-Let's hope it all works out. I don't know if I can stand to see more injuries coming in those states.

Outside the building, a police car observes the fire that is spreading through the building. Watching the firefighters who have entered, a man becomes nervous about what he was witnessing.

-10-25 Adam, the fire is spreading more and more.

-understood, 10-25. 2 more trucks are coming, but they are a few miles away from the site.

-There's not enough time.

"A challenge for a police officer is to risk his life by arresting criminals. Even knowing that he may not come back alive, his oath to protect people who may be defenseless. Every day, a policeman dies, the victim of a criminal. Each one of the people sworn to protect this city, little by little, is at risk to help the city.

The fireman next to the trio runs, trying to find their way out of the building they were in, but slowly, the structure begins to collapse.

At Chicago Med, more patients begin to arrive, with burns on their bodies, further worrying the doctors and nurses.

-How did all this happen?

6 months earlier...

Brigade 51...

A man walks toward the scene. 5'7", black hair, somewhat short, wearing a shirt and jeans. A smile covers his face as he begins to walk to the entrance of the Battalion. He is surprised to see the members of the place. New firemen and veterans, the paramedic team. Feeling a little nervous, he tries to hide his nervousness by entering the place, until suddenly a man interrupts, calling him.

(Casey) - What are you doing here?

He turns around, looking at the fireman.

-I'm looking for Matthew Casey.

(Casey) - It's me. How can I help you?

The man walks toward Casey, extending his hand to the renowned firefighter.

-My name is Marcus Williams. I'm the new cadet in the Battalion.

(Casey) - Are you the cadet the department said they were sending to be part of the 51?

(Marcus) - That's right. I did all kinds of training possible before I was sent here.

-Are you military, by any chance?

-Why the question?

-It seems to be assuming a position of meaning.

-I was in Afghanistan for two years. In Kandahar. I came to Chicago because I wanted to make the best of the city, so I became a firefighter.

(Casey) - What motivates you to be part of the fire department?

-The will I have to save people and help serve Chicago as a whole.

(Casey) - You are motivated, I have to admit. Come with me.

(Marcus) - Where are we going?

-I'd like to introduce you to the 51st team. You'll love them.

The two enter the Battalion headquarters, and the others are a bit curious about the person who had entered.

(Herrmann) - Who is your new friend, Casey?

(Casey) - Listen up, everybody: This is Marcus Williams. The new cadet of the battalion and member of Truck 81. I want you to meet the members of the Truck. This is Herrman, Otis, Mouch and Stella.

(Marcus) - It's a pleasure to meet you all.

Marcus shakes hands with each of them, and they are half happy to meet the new cadet.

(Stella) - You're actually quite handsome, you know.

(Marcus) - Thank you. I think I can say the same for you, Stella. You look radiant.

(Otis) - I think you just got hit on, Stella.

(Mouch) - In my opinion, go deep.

(Stella) - Easy, easy. One thing at a time.

(Marcus) - Well, I feel I needed a change of scenery. I have always been driven by a desire to help people, wherever I am.

-What is all this talk about? - A very deep voice took over the room, making its presence very clear.

As everyone was looking at the door, the head of Battalion 51, Wallace Boden was standing in front of everyone, with a huge smile, and going towards Marcus extending his hand towards him, who does the same.

(Boden) - So you're the cadet that Central sent to 51?

(Marcus) - Yes, sir. I'm Marcus. Marcus Williams. I came here to demonstrate my full potential and perform all the services that a firefighter should do.

(Boden) - You seem to have quite a willpower to do your job. Well. - He looks at Marcus, and walks sideways, completely nervous. - Here at the 51, we are like a family. We lean on each other when we need it. We help with every kind of problem possible. And you, Marcus, really seem to have all the potential that a fireman should have. In the fire department, the commitment, and the willpower of each individual is part not only of the job, but of our lives as a whole. This service may demand a lot from you at some point, but I want to know if you are willing to do what is necessary for this service.

(Marcus) - I'm sure of it. I have always been willing to help people, and I felt that saving lives was part of me since I was out of the country. I served in the army, trying to do good for the country. But I felt that I needed a change of scenery. So much so that I even took the test for the fire department, because I felt that what I really wanted to be when I came back was someone who was able to help and save lives. Wherever I have been, I have always done whatever it took to save each and every one that I have encountered. And I am willing to do what it takes here in the Battalion to demonstrate that, Commander.

A small smile could be seen on Boden, who appeared to be impressed by Marcus' willingness to do whatever was needed for the people. Just then, the Firehouse staff began to get excited about the man, who had a backpack in hand and was ready to get ready for his first day.

(Boden) - Very good. Go to the locker room. We have a long day ahead of us, so you better be well prepared for the calls we will receive today.

(Marcus) - Thank you very much.

Marcus stands toward the locker room, while Casey, Severide, and the rest of the Battalion stands somewhat excitedly with the new cadet. Ambulance 61 was not on site, a sign that the paramedics would be doing something outside of the Battalion. Filling supplies, who knows. But Marcus knew what Firehouse 51 was really about at that moment. Beyond just being a firehouse, they were also a family, putting themselves at risk to protect civilians and fight fires. It was a new beginning for Marcus, and one that would always put him in danger, but at least he would be doing good for Chicago.

District 21...

District 21, home of the Intelligence group led by Hank Voight. On one side, the members of the elite. The detectives who investigated the day-to-day cases involving gangs, drug dealing, homicides, and all the other cases that affected Chicago, and the people who lived in the city. On the other side, the members of the Patrol, in uniform, who go about their daily lives patrolling the city streets, doing service for the good of the city. Just then, a young policeman with blond hair begins to walk into the district, coming face to face with Trudy Platt, who is somewhat surprised by this.

(Trudy) - Are you the District's new recruit?

(James) - It's my first day here, to be honest. James Santana, at your service.

(Trudy) - Desk Sergeant Trudy Platt, and don't think that this service is something so easy.

(James) - I know the risks I'm taking, Sergeant Platt. - He sighs, with a certain understanding and fear in his body. - To be honest, this kind of life is hard, but I am willing to do anything.

(Trudy) - All right, then. - She walks sideways, picking up some documents with the new recruit's name on them. - Not always, patrol involves a bit of action. Like every policeman, we have to do some tasks like testing new cars for the department, watching for suspicious activity, and even doing tasks that not all of us like. The elite here is something that you can't even imagine.

(James) - And what would be the elite of District 21?

(Trudy) - The Intelligence Unit. She is responsible for a lot of the case solving here in Chicago. Drug trafficking, seizures, homicides, a lot of them are in her and Sergeant Voight's hands.

(James) - Being honest, I have heard a little bit about him. One of the most renowned policemen, and also a veteran in the department. Someday, who knows.

(Trudy) - To get to the Intelligence Unit, you have to give your all to get what you want. Now let's get down to business. To be a policeman, you have to have the heart and the willpower to get what you want so much. I have already prepared a patrol car for you, and your partner is eager to hit the streets. I think you two will get along very well.

(James) - Can you tell me a little bit about him?

(Trudy) - His name is Anthony Vincent. He's been in this job for three years, but he's waiting for just the right moment to be able to achieve a dream he has to be a sergeant.

(James) - Has Anthony taken the exam for sergeant, by any chance?

(Trudy) - A couple of times, but he didn't pass them by a bit. He is confident that this time, he will be able to pass the test.

(James) - All right, then. Wish me luck.

So James started walking toward the courtyard, about to get ready for his first day on the job. Trudy looked at the newcomer, with an enormous concern for what was happening. The feeling of being a policeman had its price with every step he took, but it was necessary to have the willpower and the courage to go out on the streets and patrol the city, without encountering any risks.

Chicago Med...

Among a group of final-year medical students, the head of psychiatry at the Chicago Med Hospital, Daniel Charles, stood facing the group, about to begin their final year, before they choose the hospitals to begin their residencies there. A man with short black hair looked at Daniel, with an almost imperceptible feeling of concern in his body. Cameron Smith. His eyes locked on Charles', almost trying to understand what he should do. His job as a student also involved figuring out every procedure and saving lives, in the worst possible moments. But he also felt an enormous fear at what was happening.

(Charles) - Welcome. I'm Dr. Charles, the head of psychiatry at Chicago Med. These presentations were supposed to be Dr. Lanik's, but he had to go away for a trip and solve some problems, so I will take over these presentations for him until he returns. - He sighs, a bit worried. - As everyone knows, to be a doctor is to take decisions that many don't expect you to take. Fear is not always visible, but it is close at every moment of our lives. One wrong step can define the future of their careers. Even a simple slip, or decision in a fraction of a second defines what will shape you. By the end of this year, you will leave here not as students, but as future medical residents. So stay tuned to what happens around you. Catalog the events, because any detail, even the tiniest, can be crucial from here on out.

Then Charles starts walking, along with the medical students, including Cameron, who felt a great deal of concern about all this. He knew the risks he was taking, but he seemed to be driven by a will to save people, no matter what. In this, he comes face to face with Will Halstead and Natalie Manning, who feel a tension with the medical students who have entered the hospital.

(Natalie) - The first day you never forget, do you? - She looks at Cameron, as if the question was directed at him.

(Cameron) - I am afraid to see what will happen next. The uncertainty of this profession is somewhat difficult for me.

(Will) - We've all had a rough first day. But I think you have a lot ahead of you.

(Cameron) - I appreciate it.

(Charles) - Cameron? - He looks at the medical student, getting his attention. - Would you please come back here?

(Cameron) - Sure.

The uncertainty of the rookies in Firehouse 51, District 21, and Chicago Med was enormous. Marcus was willing for his first day, but James and Cameron had their uncertainties, but the willpower to do whatever it took. The trio, in their professions, still had a long way to go, and very soon, they would face their first calls to duty. These were their stories. But we are just getting started in all this.

To be continued...

Author's Note: To be honest, this story is a crossover between Chicago Fire, Med and PD, introducting new characters who will provide a day to day basis about the challenges and hardships about the jobs taken by our protagonists, but I can guarantee to all of you that the One Chicago franchise characters will also have an important part in this plot, and you will be surprised for what is going to happen in this story. I just couldn't put three categories as a crossover because of the rules. It will be very faithful to the series in question, and you will watch some times unlike any other. This may be a tough story, as a drama like this, some cases can be tough and hard, but you will be surprised about what will happen here, folks.

That's it for today, dear readers!