Firehouse 51 deals with the aftermath of the capsized boat rescue. Gallo, Ritter and Violet discuss plans for a side gig.
A video of Casey from the roof rescue goes viral. Mouch sets up a Little Free Library at Firehouse 51. Herrmann breaks protocol.
Griffin learns the truth about his father's death and reveals why he really came to visit Casey. Gallo, Ritter and Violet take steps to expand their microbrewery business.
Kidd spreads her wings as a lieutenant. Chief Hawkins rides with Ambulance 61 to learn more about Brett. Casey takes a trip out of town. A Ritter date night turns into an emergency situation.
In the show's milestone 200th episode, Casey makes a life-altering decision. Gallo, Ritter and Violet agree to an interview and photo shoot. Brett and Mouch launch the paramedicine program. Cruz comes closer to fatherhood.
A major security breach in the city's computer networks forces Firehouse 51's senior leaders to take matters into their own hands. Severide gears up for an arson investigation.
Gallo clashes with the new lieutenant temporarily filling in for Casey. Severide closes in on a dangerous and deadly arsonist.
Severide and Herrmann clash over office space. Boden looks at Pelham's past as he considers making him permanent. Gallo's resentment of Pelham comes to a head. Brett and Ritter force Violet to confront her true feelings for Gallo.
Gallo, Violet and Ritter debut their microbrewery business at Winterfest. Brett prepares to present her paramedicine program to an oversight panel. Firehouse 51 gets in the holiday spirit.