When the son of an influential former officer is implicated in a murder, Moore pressures Voight to charge him quickly; the stakes are raised in Atwater's fight against the blue wall after patrol officers stop responding to his team's calls.
As they await news of Halstead's fate, the team turns their attention to an illegal arms dealer; Atwater discovers his brother is in Chicago and could be tied to the case; Voight must deal with Halstead's shooter; Burgess makes her decision.
Ruzek and Burgess' secret begins to have severe implications for their police work; a series of deadly acts of vandalism causes tensions to run high in the insular neighbourhood of Canaryville; Atwater tries to reach out to his brother.
The investigation into a drug-related homicide is hampered by the neighbourhood's no-snitch culture; Upton is asked about Ruzek's rough altercation with a suspect.
A dark, secret scam is uncovered when Intelligence busts a meth lab. They discover an internet scam involving children, adopted from foreign countries, that are being sold online.
