Tracy Spiridakos

An entire apartment complex is forced into quarantine when cases of the deadly virus turns into an epidemic.

Kidd and Severide's honeymoon is interrupted by a dangerous person from their past. Kidd's former academy classmate joins Firehouse 51. Brett and Violet reflect on their relationships.

After a video is posted online showing the beating and murder of a man burnt alive, Intelligence tracks down a group of vigilantes torturing and killing sex offenders.

Mouch and Ritter work together to solve a murder mystery; Severide and Cruz tackle a food truck fire; Gallo goes to see Hawkins about Violet.

Lindsay deals with the consequences of her actions when her mother is suspected of murder. Meanwhile, Lugo gives Voight an ultimatum.

Intelligence investigate a bank robbery which leads them to a teenage gang run by an older criminal. Another detective from the robbery-homicide division tries to take over the investigation.