S4, E6: Chief Boden (Eamonn Walker) meets his new neighbor (guest star Ilfenesh Hadera), who asks him for a favor that leads to serious consequences. Severide (Taylor Kinney) takes offense to being treated like a candidate by Captain Patterson (guest star Brian White) by undermining him during a call, and the situation reaches a boiling point. Cruz (Joe Minoso) receives a surprise visit from his past when Freddie (guest star Ralph Rodriguez), a gangbanger who knows Cruz's brother Leon, comes to visit and ask for a favor. Elsewhere, the team is called to a harrowing scene of an 18-wheeler and receive a thanks in the form of tickets to see the band Rush, much to Mouch (Christian Stolte) and Herrmann's (David Eigenberg) delight.