S4, E9: Severide (guest star Taylor Kinney) is brought into the District for questioning after his car is found to have caused a deadly crash. As the investigation gets underway, the team works to uncover a group of car jackers who may be the key to Severide's innocence. Meanwhile, Voight (Jason Beghe) pairs Burgess (Marina Squerciati) with Olinsky (Elias Koteas), who has a hard time feigning his excitement about this new partnership, and Lindsay (Sophia Bush) considers meeting her estranged father who is now out of prison.