The story of firefighters in Chicago.
Cast: Jesse Spencer, Taylor Kinney, Monica Raymund, Lauren German, Charlie Barnett, Yuri Sardarov, Christian Stolte, Eamonn Walker, Anne Lockhart, David Eigenberg, Joe Minoso, Randy Flagler, Don Kress, William Smillie, Steve Piper, Teri Reeves, Mo Gallini, Nicole Forester, Kathleen Quinlan, Anita Nicole Brown
A warehouse fire puts the squad in danger; Herrmann tries to make a young boy happy.
Cruz faces a possible suspension from the fire department for an off-duty incident. In other events, Casey goes head-to-head with a big politician to get his measure for first responders passed; Lt. Severide makes life difficult for new team member Jason Kannell; and Dawson gets an unexpected visit from her father.
Casey goes to drastic measures to help Kannell; Severide helps an old widow come to terms with letting go, but realizes he may be the one needing help; Otis and Cruz find a new roommate to move in; and Dawson and Brett get crafty to save a young girl.
Casey is reunited with an old colleague when the squad's rig breaks down in the field.
Dawson and Brett have a new trainee assigned for their shift; Severide's father pays him an unexpected visit.
When similar car accidents uncover the fact that someone may be targeting innocent people, a determined Dawson takes matters into her own hands to help push things along, meanwhile Casey tends to his Alderman's duties.
When a turf war escalates, truck and squad members find themselves caught in the middle as unsuspecting hostages when a group of armed gang members take cover and assume control over Firehouse 51. The situation turns even more dire when one of the infiltrators is wounded.
Firehouse 51 responds to the scene of a blaze that puts many lives in danger, including someone related to a Chicago police officer.
Members of Firehouse 51 are split up and reassigned to various houses in Chicago by Chief Anderson.
A superior comes after Boden for making a split-second decision in an accident that overrides him.
CPD intervenes when Casey and the squad are targeted by a man who has a grudge against them; a pal of Severide's father shadows the squad; Brett's relationship with Antonio hits some turbulence: his ex-wife; and Casey has a gift for Dawson.
Dawson tries to keep her emotions in check during an ambo run involving a pregnant teenager, while Casey is forced to make a split-second decision regarding two victims in need of assistance and deal with the repercussions.
Severide agrees to donate bone marrow, but an accident throws everything into flux; Casey and Dawson seek some peace at home; and Otis and Mouch film a PSA encouraging folks to join the fire department.
Dawson and Casey meet Louie's biological father. In other events, Severide goes back into old habits as he tries to help Anna with a bone marrow procedure and Brett opens up to Dawson.
Casey and Dawson face a hurdle in their quest to adopt Louie; Severide receives an interesting proposal from a firefighter-turned-medical student; and Otis convinces Herrmann to throw a bash in honor of Molly's 100th anniversary.
Gabriela and Antonio's parents come to Chicago for their anniversary, while Chief Boden discovers a secret about his stepson.
Dawson hits a pedestrian while responding to a call; Casey and Severide investigate an arson; Boden decides whether to attend a function in New York; and Casey puts Herrmann at the helm for a shift.
Casey is unable to save a woman from a burning house; and he and Severide disagree over the fire's cause. Also: Herrmann is out to catch a mystery tagger who's targeting the firehouse; Boden receives a surprise visitor; and Dawson and Brett respond when a teen boy is injured during a romantic homecoming proposal.
Casey is forced to take extreme measures when a forklift accidentally pierces a tank of acid, causing it to spill and putting a father and daughter in danger.
Susan Weller helps Casey with an urgent personal matter involving Dawson
Members of 51 end up in a dangerous situation while responding to an auto accident and Stella must make a serious decision about her ex.
Severide and Stella search for Grant, who's AWOL from Chicago Med; Dawson questions her career path; Casey's relationship with his political consultant cools; and Borrelli's anger at Boden over his brother's death boils over. In other events, Mouch and Brett partner on a new venture.