9-1-1: Lone Star preview reveals how Grace's absence is explained after Sierra McClain left show (exclusive)

As 9-1-1: Lone Star co-showrunner Rashad Raisani puts it, you would not be reading about the Fox first responder drama if it wasn't for Sierra McClain, who spent four seasons on the series as 911 call center dispatcher Grace.

"If not for her, we wouldn't be talking right now," Raisani told Entertainment Weekly last week while previewing the upcoming fifth and final season of Lone Star. "She's a central piece to the show. She's the voice on the phone of the title, you know what I mean?"

All that said, McClain chose to abruptly depart the show while on hiatus after last year's season 4 — leaving fans wondering how her absence would be addressed, given that Grace's husband, Judd (Jim Parrack), and daughter, Charlie (Kobe Melton and Kodi Melton), remain on the series. Now, a preview clip exclusive to EW provides our first clues ahead of Monday's season 5 premiere.

In the clip above, Judd surprises his son Wyatt (Jackson Pace) with a new home. We also learn that Wyatt and Leigh Ann (Jessi Case) have had a son, Leo. Standing next to Wyatt's mom, Marlene (Robyn Lively), Judd asks to take a family photo. "Y'all, lemme get a picture of this for Grace. She would kill me if I didn't," he says. "Gracie told me she's sorry she can't be here."

"Well, I'd say she's got much more important things on her plate right now," Leigh Ann replies. "Mama's...Mama's doing the Lord's work," Judd explains in agreement.

So while it's not explicitly clear just yet, it's fair to assume Grace, who has always been very vocal about her faith, is off doing some sort of missionary work — a development that intentionally leaves the door open should McClain ever decide to return to the series. (Though filming for season 5 is complete and, unless the series is saved by another network or streamer, Fox has announced the show will not be returning for a sixth season.)

In our interview with Raisani (done prior to the cancellation announcement), the co-showrunner and executive producer revealed he would welcome McClain back whenever she's ready. "As I told her, 'Any time I'm here, there'll always be a place for you,'" he said. "I would love it, I'd beg her. But [her departure] did force us to do some unexpected things that led to some beautiful storylines."

One of those storylines also solves another problem caused by Grace's absence: Wyatt not only has a new home but a new job, taking over as the show's central 911 dispatcher.

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"We wanted to show that no matter what your physical situation is, you have so much to offer," Raisani explained. "I'm proud that we're able to tell that story for a lot of people who may have something that makes them feel like they have struggles, but to see that there's always ways that you can do something great. So [McClain's departure,] I think, ended up being a fortuitous thing in allowing us to go bigger with that storyline."

9-1-1: Lone Star season 5 premieres Sept. 23 at 8 p.m. ET on Fox.