Things will get personal for Kim (Marina Squerciati) in the upcoming episode of "Chicago P.D." season 4.

Titled "Last Minute Resistance," this week's episode will see Kim's sister become a victim of a sexual assault. According to the official synopsis, Kim encourages her sister to go out and spend a night out with friends. The next day, Kim wakes up to learn that her sister Nicole (guest star Jules Willcox) never made it back home. Feeling guilty about what happened, Kim seeks help from the Intelligence team to find her missing sister. The search for leads eventually takes an unexpected turn when Nicole is discovered fighting for her life in an El station.

NBC recently released a new promo for the episode, which starts off with Kim telling Hank (Jason Beghe) about Nicole. When Kim finally sees her sister in the station, Hank assures her that Nicole's sexual assault case will be the team's main priority. "An attack on your family is an attack on our family," he says. The clip later reveals that the case is not just a random back-alley attack. Instead, Nicole has been targeted by someone who knows her well. The agents later find out where the suspect lives and, upon searching the apartment, they discover different photos of women he has probably been stalking.  At the end of the teaser, Kim can be seen tackling the suspect.

Meanwhile, the One Chicago world is having a major behind-the-scenes change this season. Executive producer Matt Olmstead will be leaving the interconnected "Chicago" franchise after the current fourth season ends. Deadline reports that NBC has not yet announced a replacement for the EP.

A key figure in the Dick Wolf–created shows, Olmstead served as the executive producer of "Chicago Fire" before co-creating the spin-off "Chicago P.D." He reportedly exited the series under amicable terms and is now taking offers for a new project.

The fourth season of "Chicago P.D." airs every Wednesday at 10 p.m. EDT on NBC.