No new 'Chicago Fire' episode tonight: When will Season 4 Episode 19 titled 'I Will Be Walking' air?

In the upcoming episode titled "I Will Be Walking," of NBC's "Chicago Fire" Season 4, Severide (Taylor Kinney) will look after Detective Holloway's 9-year-old son while she will be in an undercover operation.

Instead of airing April 12, Season 4 Episode 19 will air April 19 on NBC.

The synopsis, as stated by TV.com, reads:

"Casey (Jesse Spencer) becomes involved when a high-school student is the victim of a gang-retribution incident. Severide lends a hand to Detective Holloway, who's involved in an undercover operation, and watches her 9-year-old son at the firehouse."

"Elsewhere, Brett (Kara Kilmer) and Jimmy (Steven R. McQueen) are called to aid a woman who takes a liking to Jimmy. Otis makes a surprising discovery and Herrmann's bar-running prowess is challenged."

The promo of the episode focuses on Casey's assignment. A teenager hanging on a rail of a public transportation can be seen who is screaming for help. Casey tries to help him but she is not able to do it alone.

Hence, Casey seeks help from certain people who have political influence. However, the matter becomes more complicated when Casey's life is also endangered.

In the previous episode titled "On the Warpath," Brett witnessed a murder and was threatened by the shooter not to go to the police. Elsewhere, Firehouse 51 jumped into action when a fire broke out at a restaurant and trapped several people inside a vault.

However, unable to cope up with the situation, Mouch (Christian Stolte) backed off and told the others that he was not able to join them on the rescue mission.

Whether Casey will be able to save the student and how Severide will take care of Holloway's son, will be seen once the episode airs April 19.