In an attempt to distract Intelligence from the investigation into his son, Chief O'Neal forces Voight and the team to handle a "dead fish case." However, when that dead fish turns into a complicated heater case, Burgess is thrown back into difficult memories from her past. 

A series of brutal home invasion robberies finds the team paired with Det. 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.