'Chicago P.D.' Boss on How Upton's Latest Obsession Will Force Her to Address Halstead's Absence (Exclusive)

Chicago P.D.
Lori Allen/NBC

Showrunner Gwen Sigan talks to ET about Wednesday's fall finale.

It's led up to this. Chicago P.D.'s latest case, involving Sean (Yellowstone's Jefferson White), a trafficker of young girls who also happens to be the police chief's son, has consumed Hailey Upton's (Tracy Spiridakos) attention since Halstead's departure. Obsessed with bringing Sean in once and for all, Upton -- who hasn't addressed her husband's absence head-on just yet -- and her cohorts at Intelligence find themselves with their best chance at taking Sean down in Wednesday's fall finale.

"It's been a road, at this point, with the Sean O'Neal case. We finally at the [end] of [episode] 8 have actual physical evidence, and when we return in episode 9, we will see that even though we do have that physical evidence, it's still not enough. But now we are definitely on a clock," showrunner Gwen Sigan told ET ahead of the episode. 

"Sean knows we're coming after him. The chief knows we're coming after him, so there are a lot of obstacles and it's a pressure cooker," she previewed. "It's, 'Can we get this guy?' We are so invested, Upton especially; this has been an obsession of hers. So it really becomes, 'Can we get through these obstacles and get this man?'"

For Upton, shifting all her time and energy on the Sean O'Neal case instead of dealing with her husband's absence more directly, was an idea the writers felt aligned with who she was and how she would cope with major life changes.

"When we were in the room in June, the staff, we all liked this idea of talking about the themes of, can the broken be saved? I think all of our characters were so broken, and we knew that when Halstead left, Upton would be in this state," Sigan said. "And in true Upton fashion, she's just not going to want to address it. She's not going to want to wallow, she's not going to want to fall apart. So we loved the idea that she would get obsessed with something. It became about how can we create the most broken irredeemable person? And that was Sean to us."

"Not only is he a pedophile, but he's also a man that has made that in his head part of this philosophy, and he believes he's sacrificing the few to save the many. And it's become this huge, twisted organized crime now and with minors. It's just the darkest that you can be and I think for us, as soon as we landed on that, and when we got Jefferson White to play the character, he's added this ability to see through Upton," she continued. "He feels like he thinks this person is his kindred spirit, which is so disturbing. [Jefferson] really brought that to the character and we really wrote into it, so it got even more dark and disturbing as it went on."

Lori Allen/NBC

Though Chicago P.D. is known for throwing its officers in for a loop with sometimes devastatingly personal cases, this one is on another level of intensity. "The stakes couldn't be higher," Sigan said. 

"He's a huge villain. He believes what he's doing is right. He's found a way to make it just in his mind. And he said to us he's not going to change. For Upton, it has become such an obsession and something that she is so devoted to and has been a distraction," she acknowledged. "She's not looking at any of the pain that's beneath it. The stakes are huge for every member of the team."

Without veering into spoiler territory, the case does culminate in a dramatic, violent showdown between two characters. And perhaps one of them doesn't make it. But with Halstead gone, Sigan said Upton will have to address what's really going on with her internally and get to the root of why she's been obsessively looking for any way out.

"Yes, definitely," she promised. "The second half of the season for her arc is really having to do that when this case after episode 9 in the fallout from it, she has to go back home now. She hasn't been going home. She's just been working. She's been filling her hours up as much as possible. So when she has to go back and realizes that nothing else has changed, the state of her life is the state of her life."

"Her husband, her partner's left, he's not home, he's overseas. She can't get in touch with him. She doesn't know when he's coming back, and where does that leave her? At what point do you need to confront that and realize, 'What does this mean for us?' So she is going to have to look it in the eye. It won't be pretty. It won't be an easy thing for her because she loves him and she's so loyal to him and they're married. There's just so many things that she's going to have to look at. It'll be quite a lot of that coming up in the second part of the season."

When P.D. does return in January, the first episode back will shift the spotlight to young Officer Torres (Benjamin Levy Aguilar), where viewers will learn more about him. 

"It's a very high-adrenaline case for him and it's also morally very difficult. We get to see who he is as a police officer," Sigan previewed. "We really got to know him, I think, in the first episode where he was back home and we met his mom and we met his community and his friends, and now we will be with him in the dilemmas of policing. What does that look like and what kind of police officer is he? Those growing pains that you're now thrown in with Intelligence and working these cases where there's not necessarily a right or wrong answer."

As for a potential return in front of the camera for Jesse Lee Soffer, who exited the series as Halstead earlier this season but returns to direct a future episode, Sigan left the possibility open.

"Yeah, I would never say the door is closed," she said. "There haven't been any conversations, but we love him. It's always going to be an open door."

The fall finale of Chicago P.D. airs Wednesday at 10 p.m. ET/PT on NBC.

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