Keeler's disappearance ignites an investigation into everyone with a motive from Firehouse 51.
With Keeler a free man, Severide grows impatient and takes matters into his own hands. Meanwhile, Jones struggles to fit in as the new candidate at 51.
Severide and Chicago P.D. hunt for Katie while Dawson faces the final test of her training.
Firehouse 51 steps in when a blackout causes chaos during a frigid night in Chicago.
Casey continues to deny his lingering injuries; Shay receives stunning news about Darryl's suicide; Dawson struggles to keep a damning secret.
Dawson faces an uphill battle - and unlikely competition - as a new recruit at the academy. Meanwhile, Casey discovers a lingering injury and Mills receives life-changing news.
On the verge of closure, Firehouse 51 bands together in a fight to save the station.
Dawson and Casey's romance escalates while Shay hits rock bottom and goes MIA.
A drive-by shooting forces Cruz to make a big decision while Casey and Dawson struggle to keep their feelings at bay.
Firehouse 51 is thrust into the furnace with a train derailment.
Severide performs the save of his career, while Arthur escalates the stakes at Molly's.
Pressure is on Chief Boden to resign from Firehouse 51, while mobster Arthur squeezes a struggling Molly's for more cash.
The fallout from a deadly routine call causes a rift between Shay and Dawson. Meanwhile, Severide goes stealth in his pursuit of Hadley.
As Molly's bar continues to struggle, Mouch gets a campaign assist, and Severide targets Hadley, while Dawson makes an unexpected move. Guest starring Mena Suvari.
Casey struggles to manage Heather Darden's boys. Meanwhile, Severide goes on the offensive in pursuit of the arsonist.
While Firehouse 51 takes on new blood and new rules to avoid closure, Severide faces a dangerous arsonist.
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