'Chicago P.D.' season 4 episode 15 spoilers: Team re-investigates murder case after the victim's father tries to intervene, Ruzek returns

A desperate father takes justice into his own hands on the upcoming episode of NBC's "Chicago P.D." season 4.

Titled "Favor, Affection, Malice or Ill-will," next week's episode will see the team re-open an old case after the victim's father tries to hire a hitman to kill the suspect. According to the official synopsis, Lindsay (Sophia Bush) is tipped off about a grieving father who's planning to avenge his daughter's brutal death. To know more about the case, Olinsky (Elias Koteas) goes undercover as a hitman-for-hire.

The Gang Intelligence unit lacks evidence to arrest the original gangbanger in question, so the team agrees to re-open the murder case. Elsewhere in the episode, Ruzek (Patrick John Flueger) returns to work after completing his undercover mission. However, he is surprised when Voight (Jason Beghe) decides to assign him down to patrol duty.

NBC released a new promo for the episode, and it shows Voight briefing the team about the victim's background. It turns out that she has only been in Chicago for six months before she was murdered by a gang member. The next scene cuts to the team entering a house where they discover several murder weapons. At the end of the teaser, the background voice warns that the officers will "find themselves in the crosshairs of the city's biggest gang war."

In other news, it looks like Burgess (Marina Squerciati) may be re-assigned to desk duty in the near future. Squerciati, who portrays the newest Intelligence Unit officer Kim Burgess, recently announced that she's pregnant with her first child. On Wednesday, the actress shared the news with her fans through a sponsored Instagram post for a stroller company.

Based on Squerciati's post, "Chicago P.D." isn't planning on writing her pregnancy into the story. This means that viewers should expect to see Burgess sporting some big coats or holding things in front of her to conceal her baby bump.

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