Der neue Chief Dom Pascal sorgt für Spannungen in der Feuerwache 51. Indessen versuchen die Sänitäterinnen Mikami und Novak die Wahrheit hinter einem Autounfall herauszufinden.

Nachdem Feuerwehrmann Damon Kidds Anweisungen missachtet hat, sucht sie Rat bei ihrem Kollegen Severide. Wie kann sie Damon dazu bringen, Disziplin zu zeigen?

Nach einem Brand in einem Restaurant versuchen Severide und Van Meter die Ursache herauszufinden. Wurde das Feuer absichtlich aus einem persönlichen Motiv gelegt?

Mikami missachtet das Protokoll, um ein Baby zu retten: Sie führt einen Notkaiserschnitt bei einer Patientin durch und setzt dadurch ihren Job aufs Spiel.

Kidd und Severide schöpfen Verdacht: Sie entdecken ein Speditionsunternehmen, welches in kürzester Zeit mehrere Verkehrsunfälle hatte. Nur Zufall oder steckt mehr dahinter?

Severide wird in eine Untersuchung der Illinois State Police verwickelt, nachdem er bei einem Einsatz illegale Waffen entdeckt hat. Kidd beobachtet das Verhalten von Carver.

Severide und Chief Pascal untersuchen eine Brandstiftung. Mit den Beweisen wollen sie Captain Bishop zu Fall bringen. Unterdessen hilft Cruz Mouch bei den Vorbereitungen der Lieutenant Prüfung.

Hermann und Mouch bereiten ihre Rangprüfung vor, während Cruz rätselhafte Hinweise aus der Vergangenheit seines Bruders erhält. Carver und Stella retten einen Verletzten und seinen Hund.

Cruz's past comes back to haunt him. Severide prepares to teach an arson class at the academy. Mouch searches for a victim's next of kin.

The team responds to a crisis at a community center. Severide is forced to investigate one of his own squad members. Kidd helps a teacher going through a post-incident spin-out.

Chicago's first responders unite in the wake of a catastrophic gas explosion and fire that threaten a city government building. Herrmann reluctantly shadows Pascal while Violet, Novak and Dr. Frost take charge of triage efforts on site.

The crossover continues on Chicago Med S10E11 In the Trenches (II) and Chicago P.D. S12E11 In the Trenches (III).

Herrmann investigates the rise in missing fire hydrants and teams up with Kylie to track them down. Kidd's cousin comes to town, revealing surprising family history. Violet and Novak treat the victim of a birthday cake smash gone awry.

After a daring rescue at an adventure park, Kidd asks Severide to create a ropes course for Girls on Fire. Violet’s former nemesis returns, pleading for her help.

A surprise visitor from Novak's past joins Ambo for a late-night ride-along. Herrmann faces a mountain of Chief-level training records and incident reports. Violet catches Carver in a lie.

Kidd and Severide eagerly await big news. Pascal searches for the perfect anniversary gift.

In the face of adversity, Pascal searches for justice. Violet struggles to write a letter to Carver. Damon returns to the floater pool hoping to secure a permanent spot at 51.

Kidd connects with a troubled teen interested in Girls on Fire. Cruz, Capp and Tony wait to try out Squad’s new saw. Violet and Novak are stumped by a bodybuilder who passed out at the gym.

Deputy Commissioner Boden returns to Firehouse 51 to investigate a disastrous firefight and the surrounding mystery that left one of their own in peril.

Severide investigates an old house fire from 10 years back in which Kidd had responded. Carver and Violet search for a mystery medic who abandoned a victim. Novak looks for a roommate.

With the crew stretched thin, a performance efficiency expert evaluates Firehouse 51. Kidd and Severide bond with the mother of the baby they hope to adopt.

Kidd strengthens her bond with Natalie during a road trip. Severide investigates a car fire and uncovers surprising evidence. Violet receives a career opportunity after being featured in a local newspaper.

Severide puts his job on the line to help out one of their own. Kidd navigates Natalie’s complicated relationship with her sister. Herrmann prepares to take the Chief test.