Eamonn Walker

"I love playing a fireman!" says Eamonn Walker, who costars as Wallace Boden, the stoic fire battalion chief on Dick Wolf's Chicago Fire. The British actor, best known for his role as spiritual inmate Kareem Said on HBO's Oz, is especially thrilled now that Boden is out from behind his desk and going on calls. "How can you play a firefighter and not fight fires?" he asks with a laugh.

The chief is also finally getting some juicy storylines of his own, particularly his attempt to save a young firebug, which culminates in Wednesday's episode (10/9c, NBC). The plot further cements the chief's nurturing role among his troops. "The story [gives] insight into the chief's empathetic relationship with his 'children' in the firehouse," explains Walker, 50.

Next Wednesday, Boden has little time to dwell on that outcome when EMT Gabriela (Monica Raymund) needs his guidance after being pulled away from her job by her cop brother Antonio (Treme's Jon Seda). Their investigation into an epidemic of lethal heroin on the streets of the Windy City "opens up a whole other layer of Chicago," teases Walker.

Also keeping the chief busy is the rivalry between the injured Kelly Severide (Taylor Kinney) and Eric Whaley (Shane McRae), the firefighter subbing for him. It seems Severide is very unhappy about a piece of their shared history. "Severide is a hothead, and that heat makes him as good as he is [at his job]," Walker says. "The chief's job is to keep him from burning himself out."

That's something not likely to happen to Walker. "I haven't felt this much excitement and love on a show since Oz, which changed my life," says the actor, whose other credits include ER and Masterpiece Theatre's Othello. "This is a dream come true."

Check out this exclusive clip from this week's episode of Chicago Fire:

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