Herrmann fights for his life after being stabbed; Cruz hits the streets to find Freddie. Mouch proposes to Trudy.

The crossover continues on Chicago Med S01E05 Malignant (II) and Chicago P.D. S03E10 Now I'm God (III).

A tornado threatens Chicago. Chili makes a major mistake, which causes Brett to report her to Boden. Otis asks Dawson to help him solve his women troubles. Severide assists a Department of Homeland Security agent.

The team responds to a mass shooting; Casey investigates the missing money from the fund-raiser. Jimmy agrees to represent the firehouse in a boxing match against the Chicago PD's 21st District. Chili's behavior continues to be an issue for Brett.

Truck and squad are called to aid in a massive all-city response when an old, ill-equipped factory-turned live/work space quickly turns into a firestorm, trapping countless unsuspecting victims. The dire situation quickly turns personal when it is discovered that one of Chicago PD's own has a family member at the scene.

The crossover continues on Chicago P.D. S04E016 Emotional Proximity (II) and Chicago Justice S01E01 Fake (III).

In response to a call involving a residential fire, Otis and Kidd's lives are suddenly put in jeopardy when gunfire goes off inside the house. Dawson comforts Brett during an especially trying time. Meanwhile, Casey begins to notice that romance might be going on within the firehouse.

The crew struggles to come to terms with an injury to one of their own; a temporary replacement must be dealt with; Boden ponders some interesting news; Kidd has a hard time keeping a secret.

Firehouse 51 is faced with a daunting challenge when an out-of-control blaze consumes a 15-story apartment complex, trapping victims on the top floors. Complicating the rapidly escalating situation, members soon discover that someone close to home may be one of the trapped victims.

The crossover continues on Chicago Med S04E02 When to Let Go (II) and Chicago P.D. S06E02 Endings (III).