It's been a long, hard summer for Chicago Fire fans, who've been waiting to find out the fates of their favorite Firehouse 51 firefighters last seen trapped in a blazing building with no discernible way out. Things are not looking good for Casey (Jesse Spencer), Severide (Taylor Kinney), Kidd (Miranda Rae Mayo), Herrmann (David Eigenberg), Mouch (Christian Stolte), Otis (Yuri Sardarov) and Kannell (Kamal Angelo Bolden). Specifically, things are really not looking good for Mouch, who collapsed after suffering an apparent heart attack — on what was supposed to be his last call before retirement, no less — moments before the rest of the crew realized they were stuck.

The good news is, we'll find out in the first few minutes of Tuesday's Season 6 premiere who makes it out of the burning building. The premiere picks up literally one second after the final shot in the Season 5 finale, according to showrunner Derek Haas. Then, after that scene is resolved (gulp), there's a two-month time jump.

The bad news is, at least one character will be leaving the show in that time period. Whether that's in a body bag or not remains to be seen, but the gang will have to say goodbye to one of their own in some form this season.

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"You can expect not everyone coming back for this season but I don't want to say what causes that," Haas says cryptically.

While Haas can't reveal who's leaving the show, or why, here are eight teases he did give us about Season 6:

A new timeslot. The One Chicago flagship is moving to a new night for the new season. This fall, you can catch Fire on Thursdays at 10/9c rather than Tuesdays in the same time period, meaning it'll be up against ABC's How to Get Away with Murder.

A blast from Brett's past. Eloise Mumford is joining the cast in a recurring role as Hope Jacquinot, an old friend of Sylvie Brett's (Kara Killmer) from Indiana who comes to the Windy City and promises to shake things up on Fire... not necessarily in a good way. "Hope might be a bit of a misnomer because Hope is a disrupter; she's an instigator," Haas says. "[She] comes to the big city and really gets a nice eyeful of what Brett's life is like, and likes what Brett has and what Brett's done with herself since she left [Indiana], and might think she should get a piece of what Brett has. But might not be willing to put in the same amount of work that Brett did to get where she is." Predictably, Hope — who's introduced in the first episode — also sets her sights on Severide. But, as Haas cautions, "She might not always have the best intentions."

Sylvie-Antonio 2.0? Speaking of Brett, with Antonio Dawson's (Jon Seda) impending return to Chicago P.D., will there be an opportunity for them to rekindle their romance? Haas is being coy for now, but teases that Antonio "is going to come in around Episode 7 and be around for a few."

Family matters. Chicago Fire plans to focus more on characters' lives outside the firehouse this season. In the premiere, there's a fire at the school where Boden's (Eamonn Walker) wife Donna (Melissa Ponzio) works. We'll also see Cruz's (Joe Minoso) brother Leon (Jeff Lima) return in an episode and, according to a tweet from Haas, the writers are considering introducing Severide's mother. And of course, Gabby's (Monica Raymund) father Ramon (Daniel Zacapa) is still around to cause some tension for her and (fingers crossed!) Casey.

A new chief. Don't panic — Boden's not going anywhere, but there will be a younger "guest chief" coming in to take the reins for a couple of episodes. The circumstances that bring about his arrival are unclear, but he will be very different than Boden.

A Dawson-centric episode. Gabby Dawson has never had a "showcase episode"... until now. "We're gonna put Dawson in a situation where she's alone without her firehouse family, without her uniform, without radio and gear and a paramedics bag, and stick her in one of those one-off episode situations where she's gonna have to go full Gabby Dawson to get out of a building collapse," Haas reveals.

Behind-the-scenes changes. Haas' co-creator and co-showrunner Michael Brandt announced earlier this year that he would be leaving Chicago Fire in order to focus on writing and directing feature films. (Together, Haas and Brandt have co-written movie scripts including 2 Fast 2 Furious, Wanted and 2007's 3:10 to Yuma remake.) "I said, 'Do it. I still have some stories I want to tell on Chicago Fire," Haas explains. "So I don't think you're going to see any changes in terms of the writing." In addition, director and executive producer Joe Chappelle is stepping down from his EP role because he's making a movie in Chicago, but will continue to direct episodes, Haas says. Reza Tabrizi, who has directed several episodes of Fire, will now be executive-producing as well.

More crossovers... in 2018. The Chicago franchise isn't shying away from the crossover episodes that fans know and love, but there won't be any big ones in 2017. Among the reasons: Chicago Fire will only air six episodes before it's sidelined for Thursday Night Football, and Chicago Med was bumped to midseason this year. But Haas is confident that the early months of 2018 will feature a three-way crossover among Fire, Med and Chicago P.D.

Chicago Fire returns Thursday, Sept. 28 at 10/9c on NBC.

Additional reporting by Keisha Hatchett