The staff of Gaffney Chicago Medical Centre's new ER are given a baptism of fire when the department's opening is interrupted by a train crash.

Chicago PD's Voight, Lindsay and Halstead track a victim to his last-known whereabouts in New York City, where the SVU squad get a shocking new lead.

Benson and Voight lead the investigation into a rape and murder case that turns out to be frighteningly similar to a case from New York a decade ago.

Red John's CBI mole is unmasked, which leads to an emotional confrontation between Jane and the traitor.

A mass shooting at a cinema inundates the hospital with gunshot victims, including the shooter. Dr Rhodes faces a crisis of conscience.

Rhodes and Zanetti race to save a member of Firehouse 51, April's brother struggles during his first day at the hospital, and a woman saved from a burning building leads to a bigger mystery.

Lt Severide is targeted by an arsonist, Battalion Chief Boden clashes with Gail McLeod on the anniversary of Andy's death, Shay has suspicions, and Mari visits Mouch.

A serial killer claims to have clues about the murder of another prisoner; Frankie Jr. prepares to take the detectives exam.

Sharon faces a tough decision over a patient in need of a lifesaving bone marrow transplant. Meanwhile, Dr Manning deals with domestic difficulties.

Severide is on edge after the arson attack, fearing what might be in store next. Shay and Dawson, meanwhile, plan to party away their problems.

McLeod pushes Boden toward an early retirement and chooses a potential replacement; all make known their disdain for the mole, and Shay enjoys a full social life.

Severide wants to implicate the serial arsonist, Dawson and Shay face the unexpected on a routine call, suspicions indicate Clarke is the mole, and Mouch campaigns for union president.

Severide tries to prove his suspicions about the arsonist's identity, Casey gets accustomed to his new lifestyle, and Dawson goes on a date with a regular from the bar.

Chief Boden unwillingly agrees to let Dawson and Brett go undercover; Kidd and Zach's relationship hits a bump; Cruz has a hard time expressing his true feelings for Brett.

Firehouse 51 joins forces with the Chicago Police Department to combat a massive explosion that leaves the city in carnage and one of the crew missing.

Severide comes across a boy in need of help while out on a jog. Boden and McLeod clash over the future of the firehouse. Mouch and Greg Sullivan debate on Otis' podcast.

Casey struggles with the injuries caused by his near-fatal accident, while Dawson enrolls at the Fire Academy to find a familiar face is her instructor.

An entire block of flats is forced into quarantine when cases of the deadly virus turn into an epidemic.

The team transport the victims of a terrible chemical leak to Chicago Med, where a bad situation quickly turns seriously worse.

The team is on high alert when an incident during a fire call leaves a dangerous man on the loose with a vendetta against Casey.