Boden's new neighbor asks him for a favor that could have serious repercussions. Severide is upset when he's treated like a candidate by Patterson. Cruz is visited by a gangbanger who knows his brother. The team responds to a call that involves an 18-wheeler; and is thanked with tickets to see Rush.

Boden suspects his neighbor is setting him up; Severide, who's still on probation, receives a surprise visit from his father and also learns something about Patterson that could be a game changer. Romance blossoms at a fire department gala.

Boden believes Maddox is behind Serena's accusations. Severide reaches out to Jamie, who's Maddox's lawyer, in an attempt to help. Patterson questions whether Boden can remain chief. Brett and Chili suspect that a man passed out in a garden is connected to a previous call. Otis has problems with his social calendar.

Patterson fills in for Boden, who's trying to clear his name. Severide learns where Serena may be hiding. Herrmann and Otis give Freddie a job that keeps him close by. Jimmy and Chili draw more attention then either bargained for.

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.

Freddie's father begs Herrmann to forgive his son's assault. Casey discovers that a makeshift shelter housing people displaced by the tornado may close. Casey attends a fund-raiser at the request of an alderman. Dawson and Brett experience repercussions after telling Boden about Chili's erratic behavior.