The following contains major spoilers for Chicago Fire Season 12, Episode 11, "Inside Man," which debuted Wednesday, May 8 on NBC.

When Chicago Fire actor Taylor Kinney took a leave of absence, fans panicked because Kinney was clearly the star of the NBC show. Season 12, Episode 11, "Inside Man" reaffirms just how critical both Kinney and his character Kelly Severide are to the long-running firefighter drama. The story revolves around Severide in every way possible, and by putting him in peril for the umpteenth time, reiterates his importance to Firehouse 51.

The premise of a fire truck being stolen directly out of a firehouse might sound farfetched, but it's something that has happened in real life, and it puts Kinney in his element. With the numerous action scenes that Chicago Fire has handed him over the years, he wrangles the physical part of the episode easily, while the Stellaride relationship provides emotional depth. "Inside Man" is a standalone episode -- but one that gives fans a lot to be excited about.

Chicago Fire Leans Into Its Action Element

The Taking of Truck 81 Creates an Escape Thriller

Christopher Herrmann: You do what it takes.

Threatening Kelly Severide's health and safety is a recurring theme on Chicago Fire. While the show has messed with all of its characters at one point or another over 12 seasons, Severide and his BFF Matthew Casey have particularly been through the wringer -- ostensibly because Severide and Casey were the leaders of Firehouse 51, but also because their personalities are very proactive. Severide in particular throws himself into everything headfirst. When "Inside Man" shows him hiding on the about to be stolen fire truck inside of simply trying to get away from the scene, the audience's reaction is "yeah, that's typical Severide." On any other show it would seem like a dramatic license moment, but Severide brings his own dramatic license.

From that point on, Kinney has half of the show to himself as Chicago Fire cuts between Severide and everyone back at the firehouse. There are whole beats where Kinney is acting by himself because there's only one other person in the bad guys' warehouse and Severide is trying not to get caught. That means he has to sustain the tension as Severide sneaks inside, underneath and away from Truck 81. Even in the final act, when Severide is forced into acting as the truck driver, there's not a whole lot of dialogue. With the help of now-veteran Chicago Fire director Brenna Malloy, Kinney communicates most of the episode's drama through his reactions and expressions, in addition to the physicality required to be running around and fighting people. It's almost a shame that Severide's escape from the intentionally crashed truck happens off-screen, because he would have been great in those nervous moments while viewers watched him try to get out of the wreckage.

"Inside Man" acts in contrast to Chicago Fire Season 12, Episode 10, "The Wrong Guy," which struggled because characters including Kelly Severide were forced into situations where they didn't fit -- even though they were supposed to be uncomfortable, the script went past that and felt like the whole hour didn't make sense. But here, Severide is exactly where he ought to be: in the field, leading by example. Any other character put into his place would not have carried it off as successfully as Severide did, because stories like this are true to his character and play to Kinney's strengths. And as Kinney goes, so does Chicago Fire.

'Inside Man' Also Plays to Stellaride Fans

Chicago Fire's Main Romance Gets Plenty of Screen Time

Stellaride fans who were dismayed by not getting more Severide and Stella scenes in "The Wrong Guy" will also be thrilled with "Inside Man," even though the couple's on-screen moments are mostly concentrated at the end. The Stellaride of it all is clearly communicated through the emotional roller coaster Stella goes through while worrying about Kelly. Even though Chicago Fire episodes like "The Little Things" show how awesome Stella is, the series still gives her space to be vulnerable. There are moments when Miranda Rae Mayo seems like she's about to burst into tears. And it's Stella and how the other characters support her that the firehouse scenes largely revolve around; some people like Stella's protege Kylie Estevez (a returning Katelynn Shennett) fade into the background.

Some time and dramatic space are taken up by the suggestion that new arrival Jack Damon (guest star Michael Bradway) is the titular "inside man," and frankly, that's not a half-bad idea. It would have made sense with Damon's suspicious phone call and his being the last person at the firehouse to interact with Severide -- which is why it's a great red herring. That being said, it's also somewhat surprising that Chicago Fire nixes that plot twist. The whole "Damon as an enigma" bit, with Ritter voicing his suspicions to Stella here, already feels played out -- and the total lack of reaction from Damon when Ritter tries to apologize is like letting the air out of the dramatic tires. The character hasn't shown anything to excite the audience, whether it's as a potential villain or a potential new series regular. If he had been the inside man, that would have been a quick and complete story arc for Jack Damon.

At least Ritter finally gets to open up about his new relationship when his boyfriend, Officer Dwayne Morris, is one of the cops assigned to look for Severide. The other Firehouse 51 couple doesn't fare as well: Joe Cruz reveals that his wife Chloe wants to go to couples therapy because of his increasing job hours. With Chloe not even in the episode and having missed "The Wrong Guy" as well, her character and their marriage are missing important story points to make this make sense. This feels like a sudden, sharp turn so there can be some Chicago Fire relationship drama to contrast Severide and Stella's flirtatiously happy ending.

Is 'Inside Man' the End of a Chapter for Chicago Fire?

Season 12 Changes Might Lead to Bigger Ones Ahead

Lizzie Novak: Everyone is acting flippin' bonkers.

Although Chicago Fire Season 12, Episode 11 is written very clearly as a standalone installment, the announcement of Eamonn Walker no longer being a series regular adds another element to it. Walker's character Wallace Boden misses his second straight episode, and that's fine because there's no clear path for Boden during "Inside Man." If he were present, then Stella wouldn't have to be nervously trying to handle the situation at the firehouse. While Walker is still expected to play Boden on a recurring basis, this makes Severide acting as interim boss in "The Wrong Guy" seem like foreshadowing. Will Chicago Fire have to push Severide into Boden's role more often -- and thus take the character out of where he works best? Or will Firehouse 51 just not have an on-screen boss anymore, with Boden running the operations in the background until Walker pops up for a specific reason?

"Inside Man" illustrates that Kelly Severide absolutely is not management material. He is most effective -- both within the team and in the TV show as a whole -- when he's in the heart of the action. With Casey and Sylvie Brett now married and back in Oregon, the organic progression of Severide's character is that he's got to fill that white-shirt void, but no one actually wants to see that. Chicago Fire could give those kinds of duties to Stella, who's a better fit personality-wise and whom Boden saw leadership potential in, but then how does that affect what stories she gets going into Season 13? The answer that makes the most sense from an entertainment standpoint is to just say Boden is doing all the work off-screen, and eliminate the bureaucratic headaches that Firehouse 51 always deals with. Yet that also has a drawback in that it's not realistic for a workplace where people have to handle a lot -- and sometimes get in trouble for it, too.

That's a problem for the remaining two episodes of Season 12, but it's "Inside Man" that quite firmly throws that gauntlet down. Severide isn't an office type and Kinney isn't at his best in those scenes, either. He provides the inciting energy that drives Chicago Fire forward, whether it's how Kelly Severide is always getting into trouble, or because Severide's marriage to Stella has become the heart of the show, or because all of the other characters have such respect for Severide. "Inside Man" confirms, without a doubt, that Chicago Fire isn't the same series without Taylor Kinney.

Chicago Fire airs Wednesdays at 9:00 p.m. on NBC.