Tracy Spiridakos

A spate of robberies comes to light after a firehouse lockbox key goes missing, and Sgt Hank Voight suspects a firefighter may be involved. With Boden's support, he recruits Cruz to go under cover to help sniff out any suspicious activity.

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.

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

Tensions run high between Casey and Herrmann when the firehouse responds to an apartment complex fire. After discovering something extremely suspicious during the call, Kidd and Severide do some investigating and get CPD on the case.

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.

Chief Boden unwillingly agrees to let Dawson and Brett go under cover; Kidd and Zach's relationship hits a bump; Cruz has a hard time expressing his true feelings for Brett.