After a luxury condo is robbed, the team is shocked to learn that not only was the family fast asleep when the crime occurred, but their teenaged daughter was violated during the invasion as well. Voight consults Jimmy from Firehouse 51 to confirm his suspicion that the family was knocked out by a powerful gas, and Lindsay, Halstead, Atwater and Ruzek go undercover to seek out the perpetrators. Meanwhile, Voight tries to help a former acquaintance get back on his feet, and Platt and Mouch receive disappointing news regarding their upcoming wedding.
District 21 of the Chicago Police Department is made up of two distinctly different groups: The uniformed cops who patrol the beat and deal with street crimes, and the intelligence unit, the team that combats the city's major offenses, such as organized crime, drug trafficking and high-profile murders. Leading the intelligence team is Sgt. Hank Voight, a man not against skirting the law in the pursuit of justice.
Demanding and tough, only those who can take the heat survive under Voight's command. Take Det. Antonio Dawson, for example. Despite a troubled history with his boss, Dawson has ambitions of running the unit. If that means facing off against Voight every day, he'll persevere. From the street cops with dreams of moving up to the elite crew who are already in, life on the job is a daily challenge.