In Wednesday's episode, Burgess's sister Nicole (Jules Wilcox) -- who arrived in town in last week's episode with her young daughter in tow -- is the victim of a brutal attack during a night out with a group of her girlfriends. And making matters worse for Burgess is the fact that she's the one who encouraged her sister to go out, while she stayed at home with her niece.
"This episode is really beautiful and wonderful and deals with rape in a way that is really touching and dark," Squerciati tells TVGuide.com. "Burgess really sort of has to become a different person in order to deal with her sister's rape. I think anyone would. So, as an actor, I was very excited to play it, and scared, because it's a scary thing. ... I really feel like there's a real softness to Burgess, and when I read this script I didn't see that softness at all. The second that it happens, she knows that she needs to shut that down."
In our exclusive clip from the episode, Burgess' colleagues outline the horrific details of the case and Intelligence bands together to track down the perp. After all, as Voight (Jason Beghe) tells Burgess, "An attack on your family is an attack on our family."
Chicago P.D. airs Wednesdays at 10/9c on NBC.