A riveting police drama about the men and women of the Chicago Police Department's District 21 who put it all on the line to serve and protect their community. District 21 is made up of two distinctly different groups: the uniformed cops who patrol the beat and go head-to-head with the city's street crimes and the Intelligence Unit that combats the city's major offenses - organized crime, drug trafficking, high profile murders and beyond.
Still reeling from the death of informant Anna, Voight faces a new threat as he tries to keep the neighborhood clean. New wrinkles develop in the Upton, Halstead and Voight dynamic. The team gets a new chief.
When a convicted murderer hijacks a prison van, the team scrambles to find him and the abducted prison guard before it's too late. Burgess questions Ruzek's motives in a case, creating tension between the two.
The team investigates a string of brutal pharmacy robberies, and Halstead connects with one of the victims about their Army careers. Upton suspects there is more to the story and confides in Voight.