NBC’s “Chicago P.D.” premiered an episode that delved into neighborhood gang violence this week. Season 4, episode 4 saw the Intelligence team tackle multiple shootings. In the upcoming episode, the detectives will take down a drug smuggling ring.

According to the synopsis (via SpoilerTV) of Season 4, episode 5, the detectives investigate the murder of a college student whose body was washed up in a lake. Near the body, the policemen and women find a backpack filled with a deadly drug called Fentanyl. The Intelligence team is then pressurized to find the source of the deadly drug operation.

Erin Lindsay (Sophia Bush), Hank Voight (Jason Beghe), Jay Halstead (Jesse Lee Soffer) and Antonio Dawson (Jon Seda) track down all the dealers of Fentanyl in “Chicago P.D.” Season 4. This drug is not only fatal but it has been linked to a number of deaths in Chicago.

As the team investigates, they discover a number of dealers that are a part of a college smuggling ring. The promo of episode 5, titled “A War Zone,” shows the unit finally catching the city’s most notorious crime lord. Voight informs the detectives that the police department has been after him for 15 years!

Elsewhere, Julie Tay (Li Jun Li) and Burgess (Marina Squerciati) come across a bloodied child who will expose a dark and twisted secret about his family while they are patrolling the streets of Chicago. Unfortunately, Tay will be reassigned to her original post so this may be her last episode on “Chicago P.D.”

Meanwhile, Mouse (Samuel Hunt) will cause some tension in the department when everyone learns that he wants to reenlist in the army.

This episode of “Chicago P.D.” will air after two weeks. There will be no episode of the police drama next week.

Moreover, Burgess and Lindsay will team up for an upcoming investigation in a couple of episodes, reports TVGuide.

“Chicago P.D.” Season 4 returns on Wednesday, Oct. 26 at 10 p.m. EDT on NBC.