Following a one-week hiatus, "Chicago Fire" season 4 is set to return next week with its new episode, titled "I Will Be Walking."

Episode 19 of "Chicago Fire" season 4 follows Casey, now a newly-appointed alderman of the Chicago City Council, as he makes a highly precarious deal to prevent a full-scale gang war from breaking out.

Promo video for the episode shows Casey, caught up in a growing gang war after firefighters are called in to save the latest victim of a gang. The clip shows that the victim is a high school student, bloodied and fastened to a post under the Chicago L trains.

As Casey seeks to do everything in his capacity to rescue the student, he makes dangerous deals with some nasty characters. He ends up entering those deals after realizing that it will be quite a challenge for him to find allies, considering the gang-infested neighborhood that tends not to trust authorities like him.

"I Will Be Walking" also features Severide as he volunteers to babysit the nine-year-old son of Detective Hollway, who has to be out for an undercover operation.

Meanwhile, a woman saved by Brett and Jimmy ends up having some keen interest in Jimmy. Stella, on the other hand, challenges the bar-running skills of Hermann. The two characters engage in various tasks just to prove who between them runs the bar best.

"Chicago Fire" season 4, episode 19 airs on April 17, 10:00 P.M. on NBC.