Kelly Severide will find himself in the middle of a difficult situation in the upcoming episode of "Chicago Fire." Season 4 episode 20 is titled "The Last One for Mom" where Detective Holloway continues to leave her son in Kelly's care, while she testifies in court.

It was recently revealed that Detective Holloway has been taking part in an undercover operation involving the Mexican cartel and El Chapo. Kelly is now aware of this and also knows that the cartel has threatened to hurt people close to Detective Holloway.

Although worried, Detective Holloway will testify in court, while her son is left with Kelly. Trouble ensues and Kelly will be forced to intervene with the cartel in order to save the child left under his care.

Meanwhile, Matthew Casey's good deed in the previous episode has made him a social media sensation. Videos of him escorting Victor to his graduation have called the attention of people involved in politics. A care package is sent to him, which gets him in hot seat with the Board of Ethics.

The firehouse also attends to a call concerning a burning art gallery. The trailer shows a fire survivor telling the team that someone is inside the building, which is about to collapse. The firemen are seen having difficulty with the rescue operation and a scene shows Chief Wallace Boden risking his life to get through the victim.

Sylvia is also about to find out the real result of Otis' medical checkup. She advises him to take care of himself but gets increasingly worried that he chooses to ignore his health issues. Instead, Otis spends his time preparing for the upcoming annual firefighting conference to be held in Las Vegas.

"Chicago Fire" airs Tuesday at 10 p.m. on NBC.