A new face at Firehouse 51 causes tension, while rising chaos in the city brings new challenges to the team; Herrmann stalls on plans of relinquishing his office to Mouch.

Vasquez strives to prove his worth at 51, while Violet and Novak investigate a disturbing case. Meanwhile, Herrmann works to maintain Molly's success.

When city budget cuts stretch crews thin, Pascal takes matters into his own hands. Vasquez looks to an old friend for help. An incident in the field hits close to home for Violet.

Firehouse 51 must band together after a devastating fire catches them off guard. Vasquez continues his quest for answers. Violet and Novak face an unexpected roadblock in the new training protocol.

Cruz hunts for the identity of an unknown ally. Mouch takes steps to help a friend. Vasquez must make a difficult choice.

A traffic jam puts Violet and Novak in a tough spot with a patient. Severide spends a day with Pascal. Kidd makes special efforts to help Isaiah.

Severide probes a suspicious fire at a high school. Novak receives an unexpected call. Violet has a 51 firefighter join her for an ambulance shift.

After arson affects someone close to Firehouse 51, Severide hunts for the culprit. Meanwhile, Mouch and Pascal seek innovative solutions to face looming budget cuts.

A Firehouse 51 crew member is still in danger. Cruz helps Severide investigate.

Novak begins a new romance while Vasquez copes with his father's recent release.

Herrmann feels uncomfortable when a neighborhood injury lawyer involves himself in a standard call. Station 51 receives a guest.

Pacal faces intense scrutiny after a firehouse member gets injured on a call. Herrmann deals with family issues.

Firehouse 51A responds to an airport when a passenger jet suddenly goes silent. Their discovery reveals a larger, deadly secret with consequences that could reach far beyond the runway.

Severide is on high alert to track down a reckless driver who puts one of their own in harm's way. A member of Firehouse 51 struggles with a potentially life-changing decision.

A car crash puzzles Kidd and Vasquez. Herrmann gets his chance in the spotlight. Violet and Novak deal with a moral dilemma

Severide overcomes new obstacles at the firehouse. Cruz finds himself at a loss amid family changes.

After a devastating fire erupts at a surgery center, Kidd works to hunt down the true cause. Violet, Novak and Vasquez grapple with shifting relationships. Molly's hosts its first trivia night.

While in the field, Violet and Novak are thrust into a dangerous and rapidly escalating situation, forcing them to rely on their instincts to protect both themselves and a vulnerable patient.

Severide looks into a fire at a vacant store where squatters live. Mouch writes a memoir about his life.

The brave crew of Firehouse 51 puts their lives on the line to protect and rescue the people of their city.