New episodes of Chicago Fire air Wednesdays at 9 p.m. ET on NBC, following the lives of the firefighters and paramedics who work at Firehouse 51. Season 13, episode 18, titled "Post-Mortem," premieres April 16 and will see Eamonn Walker reprise his role as Wallace Boden. The official synopsis reads: "Deputy Commissioner Boden returns to Firehouse 51 to investigate a disastrous firefight and the surrounding mystery that left one of their own in peril."

Pascal has taken over as chief in Boden's absence, and Walker shares that the team will be surprised when their former leader returns. However, there's much at stake in the installment, leaving little time to catch up. With the deputy commissioner forced to investigate his firehouse family, Walker warns that Chicago Fire could lose another cast member.

ScreenRant interviews Eamonn Walker about what Boden's return means for the first responders at Firehouse 51 and if fans will see the deputy commissioner in future Chicago Fire episodes.

Chicago Fire Season 13, Episode 18 Highlights Boden's New Job

"He's got a much bigger job. The job is very different from being the chief of a firehouse."

ScreenRant: We're so excited that you're back for an episode of Chicago Fire.

Eamonn Walker: We always said we would [be].

How was the atmosphere on set when you reunited with the cast?

Eamonn Walker: It was welcoming like no other, and I would turn around and tell you there were tears from some people. There were tears when I came and there were tears when I eventually left. I had a wonderful welcome home. It was a great, great time.

How much does Boden know about what's been happening at the firehouse in his absence?

Eamonn Walker: Now that I'm going to keep as a close secret. The shenanigans that have been going on at the firehouse in his absence—you could turn around and say it would be almost impossible for him not to have heard about it, as his job is to oversee the whole of the Chicago Fire Department.

That's true. He needs to keep a close eye on that team.

Eamonn Walker: He's going to keep a close eye on every firehouse, and so that's as much as I will give you. But the truth of the matter is he's the deputy commissioner now. He's got a much bigger job. The job is very different from being the chief of a firehouse. He's now there for the men and women of the Chicago Fire Department, and this episode highlights that.

Character Reunions Aren't The Focus Of Boden's Chicago Fire Return

"What's important is how to move forward with the potential danger that is coming from this situation."

That goes into my next question. What is the dynamic going to look like now that Boden is deputy commissioner instead of their chief?

Eamonn Walker: When they do see him, they're surprised. And they're surprised because of the nature of what is at stake. And what's at stake is a firefighter was left behind in a fire and heads are going to have to roll.

So potentially this episode that you're going to watch, everybody who is an officer or a chief is on the line to be investigated by Deputy Commissioner Boden. And so that's where we start this. It starts in a terrible place and potential of somebody dying in hospital and potential of a head rolling is what's happening during this episode.

I'm curious what Boden might think of Pascal as the new fire chief, especially because he wanted Herrmann to step into that role.

Eamonn Walker: Well, whenever anybody starts a new job, and I imagine you the first day you started, nobody starts well. Everything takes a little bit of time, but that's not what's on the line in this particular episode. This is really quite specific because of the nature of what happened in this fire with one of your favorites potentially dying. So that is what Boden is dealing with. So what's happened up until now, pretty unimportant, because maybe by the end of this episode, you may lose another member of your cast.

Given the nature of this episode, is there time for proper reunions?

Eamonn Walker: They all reunite at some point, but that's not what's important. What's important is how to move forward with the potential danger that is coming from this situation. Leaving somebody behind is a no-no for everybody. The army doesn't like it, firefighters don't like it, police don't like it. You cannot leave anyone behind and not expect repercussions for it. That's where we're at.

Boden Will Need To Investigate His Own People As Deputy Commissioner

"Imagine investigating your own family and then possibly going to have to fire one of them."

You've obviously explored this character so much after 12 years, but looking back, is there a storyline that you wanted to do that just didn't pan out?

Eamonn Walker: No, because it's a series. It's not a movie. So there were ideas that came, but what's really good about our writers, I could email them and go, "What about this?" and "What about that?" And they will always listen. That's one of the other reasons why we're such a great family. It's not just the cast. You can see the family onscreen, what you can't see is the family behind the screen.

And so it goes all the way through the production office. We have been all been doing this a long time. We are a family. So if there are any ideas that pop up, you can turn around and go, "What about this?" And they'll turn around and go, "Okay, let's give it some thought. Let's talk about it." So I don't have any regrets about that.

Over 200 episodes, I explored a lot of things. So I have no regrets about that at all because I know some of the things that I had to do were very, very challenging. And this was different because I'm coming in as deputy commissioner, but I'm investigating my own people. Imagine investigating your own family and then possibly going to have to fire one of them. It's a terrible place to be.

Is the door still open for you to return again after this episode?

Eamonn Walker: Once a part of the family, always a part of the family. If they write another episode, I will come and do it. One of my favorite things about this place of work is they're always there. They're always there for each other. And we've held each other up over many, many years. And so yeah. Once a part of the family, always part of the family.

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About Chicago Fire Season 13

From Renowned Emmy Award-Winning Executive Producer Dick Wolf

Led by Lt. Kelly Severide (Taylor Kinney), Rescue Squad 3 works closely with Lt. Christopher Herrmann (David Eigenberg) on Engine 51 and Lt. Stella Kidd (Miranda Rae Mayo) on Truck 81. Their tireless, never-give-up mindset brings them all closer together – and the men and women of Firehouse 51 are more than co-workers, they’re family.

The firehouse is under new leadership with the addition of Chief Dom Pascal (Dermot Mulroney), who has huge shoes to fill after years of guidance under the calming hands of Wallace Boden, who was elevated to Deputy Commissioner. Pascal, who has spent the last decade as Chief in Miami, has a completely different style which may rub some the wrong way. What is clear at the outset are his skills and ability to stay dead calm in the face of crises -- and his goal remains consistent in keeping the house running smoothly and his firefighters prepared to overcome all adversity that may come their way.

Check out our other One Chicago interviews:

• Showrunner Gwen Sigan (Chicago P.D.)
• Joe Miñoso (Chicago Fire)
• Luke Mitchell (Chicago Med)
• Shawn Hatosy
• Steven Weber (Chicago Med)

Chicago Fire season 13 airs Wednesdays at 9 p.m. ET on NBC.