When the drunk driver who hits a car and paralyzes a 16-year-old boy turns out to be the son of a dirty cop, Lieutenant Casey must decide whether or not to turn him in. Facing pressure and subsequent threats from the powerful and well-connected Detective Voight, Casey decides to tell the truth, inviting a stand-off. Additionally, Severide, who's fighting off the advances of the Chief's new assistant, learns he has a fractured vertebra in his neck that may never heal if he doesn't get treated, but ignores the doctor's advice so he can continue working. Meanwhile, Mills is torn between helping his mother at her restaurant and devoting himself full-time to the fire department, like his father did.
No job is more stressful, dangerous or exhilarating than those of the Firefighters, Rescue Squad and Paramedics of Chicago Firehouse 51. These are the courageous men and women who forge headfirst into danger when everyone else is running the other way. But the enormous responsibilities of the job also take a personal toll.
With big reputations and hefty egos, the pressure to perform and make split-second decisions is bound to put squad members at odds. When a tragedy claims one of their own, there's plenty of guilt and blame to go around. In the middle of a divorce, Lt. Matthew Casey tries to go about business as usual, but can't help butting heads with the brash Lt. Kelly Severide of the Rescue Squad - and each blames the other for their fallen team member. When it's "go-time", though, they put their differences aside and put everything on the line for each other. This is a look inside one of America's noblest professions.