Dermot Mulroney will exit the NBC drama in season 15, which premieres October 7. Mulroney joined the Dick Wolf procedural for season 13 in 2024. If some of you saw that season 13 I was in.” Dermot Mulroney talks filming ‘heavy’ scenes for ‘Chicago Fire’Chief’s Pascal’s season 13 storyline centered on the tragic death of his wife in a car accident. Chicago Fire Season 15 premieres Wednesday, October 7 at 9 p.m ET/PT on NBC.