Led by Capt. Matthew Casey (Jesse Spencer) and Lt. Kelly Severide (Taylor Kinney), the Truck and Rescue Squad companies work day in and day out beside each other. This tireless, never-give-up mindset brings them all closer together - the men and women of Firehouse 51 are more than co-workers, they're family.

The firehouse also includes Battalion Chief Wallace Boden (Eamonn Walker), who keeps his house running smoothly and his firefighters prepared to overcome all adversity. Paramedic Sylvie Brett (Kara Killmer) returns alongside seasoned veterans Christopher Herrmann (David Eigenberg) and Randy "Mouch" McHolland (Christian Stolte) as well as resourceful firefighters Stella Kidd (Miranda Rae Mayo) and Joe Cruz (Joe Minoso).

Completing the team are daredevil Blake Gallo (Alberto Rosende), talented and dedicated Darren Ritter (Daniel Kyri), and 51's newest addition, headstrong paramedic Violet Mikami (Hanako Greensmith).