The following reveals major plot points from tonight’s Chicago Fire Season 15 premiere.

NBC‘s Chicago Fire returned tonight with its fifteenth-season premiere, picking up after an intense Season 14 finale that left most of 51’s best with their lives on the line. While the team survived mostly unscathed, the series is looking different as showrunner Victor Teran takes the helm.

At the end of July, we confirmed the news that Dermot Mulroney would be leaving the hit series after two seasons playing Battalion Chief Dominic “Dom” Pascal. While Dom’s arrival was a bit rocky for 51, the evolution of the character really won the hearts of fans and show characters alike.

I can confirm Mulroney’s final episode was tonight’s premiere, however, the creators and writers of the show do like to surprise us now and then with appearances every now and again. Like Eamonn Walker, who portrayed Wallace Boden across the show’s first 12 seasons, made a guest appearance in Season 13.

Teran spoke to Deadline recently about the new season, and saying goodbye to Mulroney.

“We only have the one episode with him I’m sad to report. It’s just the premiere. But he plays a very critical role. We had a very hard task when when Boden left. Filling his shoes was going to be an impossible task. Dermot came in and did this incredible job, and provided a bridge to what the future is going to be,” Teran shared.

He continued, “For the first time in 15 seasons, there’s not going to be a Chief in the house. Severide [Taylor Kinney] is really going to be leading things, and that’s a new thing. We’ve been thinking about that for a while, and so we needed to close out Dermot to to give space for that.”

In the premiere of Season 15, it was also confirmed that Severide had chosen the job of Chief of Firehouse 51 over the inspector job that was also offered. However, he continues to wear his fire inspector hat, albeit privately, while trying to help Joe (Joe Minoso) prove his innocence following accusations he played a role in the Season 14 finale fire. In Dom’s last moments on the show, he gives Severide advice about treading lightly between his two passions or risk facing major consequences.

Following the news that Mulroney would be leaving Chicago Fire, he shared a statement.

“Loved every minute of it. Became friends with this incredible crew of people,” Mulroney said at a fan convention.

Mulroney also acknowledged the “incredible cast” he worked with and noted that they gave him “incredibly challenging scenes” throughout his time on the show.

Further, the actor said “they write the character off,” adding, “We gave it our all for two seasons.”

Mulroney was also a series regular on the Netflix drama series The Hunting Wives, playing Jed Banks. Mulroney revealed in May that production had concluded on the show’s second season, and yesterday, The Hunting Wives was renewed for a third season yesterday ahead of the Season 2 premiere. He also recently booked roles in two films: Moon People and the action pic Streets.