More clues surface surrounding the fire that killed Shay, leading Severide to a most unexpected source who may be able to provide pertinent information. Meanwhile, Shay's sister Megan comes to town, prompting members of the firehouse to remember Shay's life. Elsewhere, Cruz is in for a surprise when Otis's grandmother moves into their apartment, while Boden finds a way to help his dying father make the most of his last few weeks.
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.