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).

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

Violet risks her job to deliver a baby on a tragic call. Mouch, Capp and Tony help Cruz track down Javi's stolen bike. Damon's departure weighs on Severide.

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.

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.

Herrmann and Mouch prepare to take their officer exams. Cruz receives a chilling omen. Carver takes care of a dog after its owner is injured on a call.

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.

Severide and Van Meter investigate a fire at a family-owned restaurant. Pascal questions Kidd's leadership.

Kidd and Severide investigate a trucking company responsible for a string of accidents. Herrmann recruits Kylie to help get new radios. Firehouse 51 celebrates Violet's birthday. Carver's allegiances are torn.

Pascal and Severide revisit the storage facility fire in hopes of uncovering new evidence. Cruz helps Mouch take his studying to the next level. Novak prepares a proposal for Chief Robinson for a whole blood program.

After Damon disobeys Kidd's orders on a call, he turns to Severide to protect him. Herrmann searches for the perfect scent to spice things up with Cindy.

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.

A new chief shakes things up at Firehouse 51. Violet and Novak work to uncover the truth behind a car crash. Cruz keeps a watchful eye on Severide and Damon's growing bond.

Severide gets wrapped up in an Illinois State Police investigation after discovering illegal guns on a call. A bird harasses Mouch on the apparatus floor. Kidd keeps an eye on Carver.

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.