Lt. Casey, who is at the center of an undercover operation to bring down a trafficking ring run out of Nesbitt's strip club, finds himself in very dangerous territory. Meanwhile, as a result of the high turnover rate on squad, Severide gets a rude awakening when Capt. Dallas Patterson is brought in, much to Boden's dismay. Dawson confirms her suspicions that her life is about to change forever and Jimmy Borrelli, the new candidate, makes an unusual first impression. Elsewhere, citizens of Chicago band together to take charge of their neighborhood in protest of a drug den in their area, resulting in ramifications that severely hinder members of Firehouse 51, who are called to the scene to battle a blazing fire.
Season 4 Episode 1 of Chicago Fire was watched by 7,370,000 viewers, resulting in a 1.80 rating in the 18-49 demographic.
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.