7. Season 4
Big trouble is brewing for multiple members of Firehouse 51 in Season 4 of “Chicago Fire,” starting with accusations of assault and battery against Chief Boden by a seductive neighbor. Levied with charges of brutality, the squad rallies together to try to get to the truth and clear his name. On the other end of the firehouse, Casey takes an undercover assignment investigating Nesbitt’s club, which is believed to be at the center of a human trafficking ring.
Meanwhile, Dawson is also dealing with a major upheaval, as her recently discovered pregnancy forces her out of the firehouse and into a desk job. But when she collapses one day at work, she risks losing the pregnancy in a stunning turn of events that will change their lives forever. The year’s crossover is kicked off in “The Beating Heart,” which begins with Hermann being brutally stabbed and requiring immediate life-saving surgery, leading into episodes of “Chicago Med” and “Chicago P.D.”
Standout episodes this season include “The Sky is Falling” which deals with a mass shooting, and “Last One for Mom,” which puts Severide in the middle of one of the most emotionally gut-wrenching stories the series ever saw when Detective Holloway leaves her son in his care and tragedy strikes. Season 3 closes out with “Superhero,” in which the death of a loved one creates a troubling situation for Borelli, while Casey and Dawson fight to foster a young boy who they saved from a fire.
6. Season 3
Season 3 of “Chicago Fire” couldn’t quite match the brilliance of its previous year, but it’s still a solid entry. It also picks up right where the cliffhanger episode “Real Never Waits” left off, with members of Firehouse 51 trapped inside a burning building that had exploded before the credits rolled, leaving their fate up in the air. The Season 3 premiere begins with the shocking death of a major character, and the crew finds it hard to cope with the loss.
Things get worse, however, when it’s learned that the explosion was no accident, and an arsonist may have targeted them. Severide, however, feels responsible for the tragedy and decides to track down the person responsible, ultimately learning that their friend’s death wasn’t the perpetrator’s first victim. Otis, meanwhile, gets suspicious of a new squad member, who may be lying about having faulty equipment.
Season 3 also features the episode “I Am the Apocalypse,” which puts the crew in peril at the city hospital when a deranged psychopath holds the entire building hostage under threat of a deadly airborne toxin. The episode was a backdoor pilot for the third franchise series, “Chicago Med,” and is still one of the best episodes of the series. The season also includes “Nobody Touches Anything” and “We Called Her Jellybean,” episodes that serve as part of two separate three-way crossovers with “Law & Order: SVU” and “Chicago P.D.”
5. Season 5
Season 5 of “Chicago Fire” successfully tops the previous season with multiple ongoing stories that begin with Severide and Stella coming under attack from a vengeful ex-boyfriend who has escaped confinement at a psychiatric hospital. Then it’s Casey and Dawson dealing with the addition of a new family member, foster child Louie. But when questions arise about their situation, it puts them in possible jeopardy even as they hope to adopt the boy officially.
In a somewhat more light-hearted subplot to the season, Brett and Mouch team up to write an erotic novel and try to have their work published. But the fun stops when their little side project is discovered and Boden isn’t happy, threatening both of their jobs. Yet another ongoing story involves Severide’s obsession with finding a bone marrow donor for a patient in need. In the first crossover installment, “Some Make It, Some Don’t,” the custody battle over little Louie comes to a head, in a story that concludes in an episode of “Chicago P.D,” while the episode “Deathtrap” begins a three-part story about a warehouse fire that continues through “Chicago Justice” and “Chicago P.D.”
“My Miracle” ends the series with a top-notch finale that features guest appearances from World Series champs Kris Bryant, David Ross, and Jake Arrieta, of the 2016 Chicago Cubs. But it’s not all fun and games, because the story also sees members of the firehouse trapped in a burning building in a harrowing life-or-death battle in an eye-popping cliffhanger.
4. Season 9
As we continue our journey up the rankings of “Chicago Fire” seasons, we find ourselves at Season 9, a season seriously affected by multiple real-world events. Shortened to 16 episodes due to the COVID-19 pandemic, an episode scheduled to air on January 6th was also preempted due to the attack on the U.S. Capitol. The season also makes the bold choice to incorporate COVID-19 into its story, as the pandemic continues to spread and the men and women of Firehouse 51 are on constant alert to help respond to the growing global crisis.
As the season opens, Kidd is chosen by Boden to take the Lieutenants exam, for a possible promotion that later ruffles feathers in professional relationships. While all of that is going on, Brett and Casey must finally confront their feelings for one another after a fateful kiss, but dealing with their emotions isn’t as easy as they might think. That’s not the only relationship that sees problems, though, when Severide begins to wonder about his future with Stella.
It all leads up to a proposal, with the pair getting engaged, while Brett and Casey profess their love for each other and consummate their relationship by the end of the season. If you’re looking for this season’s best episode, it might be “My Lucky Day,” which puts Hermann and Cruz into a stuck elevator crisis. In the season finale, “No Survivors,” the squad handles an accident at sea, forced into a rescue involving an overturned boat.
Read more: Top 3 Must-Watch Chicago Seasons with the Highest Ratings
