Chicago P.d. - Season 4 -

A crossover with Chicago Fire (Season 5, Ep. 9) where Kelly Severide is suspected of vehicular manslaughter.

Season 4 marked the end of an era for two of the show's original leads and introduced a future mainstay: Chicago P.D. - Season 4

In the season finale, Lindsay resigns from the Chicago Police Department to accept a position with the FBI in New York after being investigated for her conduct during an assault on a suspect. Off-screen, Bush cited abusive behavior and harsh working conditions as her reasons for leaving. A crossover with Chicago Fire (Season 5, Ep

Season 4 featured several "One Chicago" crossovers that connected the unit to Chicago Fire and Chicago Med : Off-screen, Bush cited abusive behavior and harsh working

In "All Cylinders Firing," Desk Sergeant Trudy Platt (Amy Morton) is brutally attacked outside her father's home, leading to a personal and harrowing investigation into her past.

A crossover with Chicago Fire (Season 5, Ep. 9) where Kelly Severide is suspected of vehicular manslaughter.

Season 4 marked the end of an era for two of the show's original leads and introduced a future mainstay:

Season 4 featured several "One Chicago" crossovers that connected the unit to Chicago Fire and Chicago Med :

In "All Cylinders Firing," Desk Sergeant Trudy Platt (Amy Morton) is brutally attacked outside her father's home, leading to a personal and harrowing investigation into her past.