Ruzek reunites with an old colleague to take down a crime ring, but when things don't add up, Voight and Burgess do some investigating of their own.
Ruzek's search for the daughter of an old family friend leads the team into a serious drug investigation; Burgess and Ruzek struggle to move on from the emotional aftermath of Makayla's abduction.
Nurse Lockwood is arrested for refusing to run a DUI blood test. Dr Halstead seeks advice about his impending lawsuit, and Dr Manning has a difficult case.
Dawson tries to help her brother Antonio unravel the details of his drugs-and-gang investigation, and goes behind his back in asking an unlikely source for assistance.
A series of brutal home invasion robberies finds the team paired with Detective Borkowski, an old friend of Ruzek's, to work the case; things get complicated for Torres when it becomes clear Borkowski has a vastly different policing style.