The cameras will begin to roll for the fourth season of "Chicago P.D." this week.

According to Reel Chicago, the police procedural drama will begin filming on Wednesday, July 20, together with other Chicago-based action series such as "Chicago Fire" and "Chicago Med."

Jesse Lee Soffer, who portrays the role of Detective Jay Halstead in the series, updated his Instagram followers that he was already preparing for his first day at work on the set of season 4. He posted a photo of the Chicago skyline as viewed from the plane.

Details of the new season of "Chicago P.D." are still under wraps, but executive producer Matt Olmstead told Entertainment Weekly in June that the series will introduce a new character early in the season.

Olmstead said, "We are setting in motion new blood coming in the beginning of next season." The new character will reportedly fill in the spot left by Patrol Officer Sean Roman (Brian Geraghty), who left the show at the team at the end of season 3 after Patrol Officer Kim Burgess (Marina Squerciati) refused to run away with him.

But it does not mean that the new character will also replace Roman in Burgess' heart. In an interview with The Hollywood Reporter in May, Olmstead said that Burgess will stay away from the dating scene for the upcoming season.

"Next year, we want to play... We'll see, we're still just kicking around ideas for next season but there's certainly a pitch for a vow of celibacy for her," the showrunner said. "In that she was engaged to a guy upstairs, she was romantic with the guy that she was working with, both of those kind of went sideways on her. there's a part of her that has to recommit to the job and her next boyfriend's probably going to be a mailman."

Viewers should also look forward to what's next for the Chicago P.D. Intelligence Unit head Hank Voight (Jason Beghe), who appeared to be bent on avenging his son's death at the end of the previous season.

"Chicago P.D." season 4 premieres on Wednesday, Sept. 21, on NBC.