Melissa Carlson

In responding to a call Atwater (LaRoyce Hawkins) and Burgess (Marina Squerciati) discover a gunshot victim and the only witness is Lexi Olinsky (guest star Alina Taber). The shooting is tied to a Latin gang. To protect Olinsky's (Elias Koteas) daughter, Voight (Jason Beghe) takes the case from the Gang Unit. Ruzek (Patrick Flueger) pulls up Burgess to help with an undercover mission that he hopes will help solve the case.

As Antonio’s (Jon Seda) life is now in question, Voight (Jason Beghe) and Platt (guest star Amy Morton) open up about their pasts. Jin (Archie Kao) is caught while tinkering with Voight’s computer and uses the only scapegoat possible to keep him in the clear. At the same time with Charlie (guest star Billy Wirth) back in town Lindsay (Sophia Bush) realizes she’s going to have to come clean about a few things. Halstead (Jesse Lee Soffer) finally gets answers he’s been wanting about Voight’s and Olinsky’s (Elias Koteas) past.

While Platt (Amy Morton) tries to manage a chaotic desk area, a man struggling to get her attention takes a drastic action and demands that the unit find his missing daughter. At the same time, Commander Fischer (guest star Kevin J. O'Connor) informs Voight (Jason Beghe) that Bunny (guest star Markie Post) is bringing up new accusations on a case from his past. Lindsay (Sophia Bush) urges her mother to fix the situation. Meanwhile, Antonio (Jon Seda) is shocked to learn a secret Olinksy (Elias Koteas) has been keeping.

After surviving a hit against him, Voight (Jason Beghe) is convinced the culprit is a criminal he and Olinksy (Elias Koteas) once put away and is determined to catch him before he injures anyone else. At District, Atwater (LaRoyce Hawkins) accidentally spills information about Ruzek's (Patrick John Flueger) past which unsettles Burgess (Marina Squerciati) and Platt (Amy Morton) assigns Burgess and Roman (Brian Geraghty) a high society dognapping case.

Olinsky's (Elias Koteas) daughter remains in critical condition following a massive fire leaving Intelligence on edge, but more determined than ever to track down the suspect. Voight (Jason Beghe) opens up the case, knowing that he has Stone (guest star Philip Winchester) and his team's full support in the investigation, and all of Firehouse 51 behind him to examine potential origins of the fire. Intelligence works to connect the dots between the building owner, those who were inside, and a string of potential suspects.

Intelligence sets out to find a missing teenaged boy who they believe poses a serious threat to the students at his wealthy school after finding disturbing drawings in his notebook. Meanwhile, Atwater (LaRoyce Hawkins) is eager to make a good impression on a prominent African American police Captain (guest star Eamonn Walker) and Olinsky (Elias Koteas) and Michelle (guest star Madison McLaughlin) find themselves in a difficult situation and turn to Ruzek (Patrick Flueger) and Burgess (Marina Squerciati) for help.