A young bystander is shot during a difficult operation; Chief Lugo reviews the shootout and Halstead becomes a key player in the outcome.
A patrol officer becomes a suspect when a van explodes during a Chicago street festival; Burgess, who helped train the officer, is desperate to prove his innocence.
The investigation into a murder of an illegal immigrant is hampered by the perception of police among the city's immigrant population.
The investigation into a drug-related homicide is hampered by the neighborhood's no-snitch culture; Upton is asked about Ruzek's rough altercation with a suspect.
A meth lab bust uncovers a scam in which children adopted from foreign countries are abandoned, then sold online; Atwater struggles with decisions about moving his siblings to a safer environment.
A family is killed, and the team searches for a drug dealer with a likely connection; Voight asks Vice Sgt. Sean McGrady for help.
Halstead goes under cover to stop an ex-military kidnapping crew from killing an innocent child.
When one of Voight's friends is found passed out in his hotel room with a dead Ukranian girl, Intelligence discovers the murder is connected to a sting and Burgess' boyfriend.
The death of Judge Tommy Wells' daughter puts Intelligence on the track of a pill mill spreading into the suburbs of Chicago and the doctor enabling it; Voight discovers who's been leaking information from the 21st.
Halstead puts his career on the line to help solve a case with ties to his new girlfriend; Voight finally discovers the mole in his unit.
Burgess works with her first criminal informant to track down a ruthless pimp and break up his prostitution ring.
When Atwater disappears at the house of a convicted felon, the intelligence unit rallies to rescue him before it's too late.
The team works with a visiting detective to put an end to a gang's brutal tactics; Antonio learns that the detective has a hidden motive for being in Chicago; Voight learns that the body of his son's killer has been found.
A basketball star is found murdered after an anti-police rally; a politically charged environment must be navigated while tracking down the killer; complicating matters further, Woods' daughter Brianna is tangled up in the case.
Intelligence tracks down a vigilante who is killing rapists; Burgess begins to question if the men who attacked her sister truly paid for their actions.
A string of bombings is targeting members of the media; the team enlists firehouse 51 to help examine the devices and prevent the next attack.
When a prominent alderman who is known for his urban revitalization efforts is killed, Intelligence looks into the corruption haunting his neighborhood; Olinsky feels pressure after receiving an ultimatum from Woods.
Upton brings back an old undercover identity to help take down a meth ring spearheaded by a former contact; with pressure from Woods mounting, Voight calls in a favor for Olinksy.
A string of robberies leads back to an unlikely individual; Voight confronts a key witness in the Bingham investigation.
Voight witnesses the kidnapping of a young woman with a mysterious connection to his past; intelligence works to find a connection between her kidnapping and several bank robberies; Olinsky gets one step closer to standing trial for Bingham's murder.
Halstead and Atwater go under cover to prevent military-grade weapons from hitting the street; Voight calls in a favor to clear Olinsky's name for Bingham's murder.