When Lindsay is tipped off about a grieving father looking to avenge his daughter's death, Olinsky goes undercover as a hitman-for-hire. With Gang Intelligence lacking enough evidence to arrest the original gang-banger in question, the team works to reinvestigate the case. Ruzek comes back after finishing his undercover assignment only to have Voight knock him down to patrol duty.
Elenco: Jason Beghe , Jesse Lee Soffer , Marina Squerciati , Patrick John Flueger , Laroyce Hawkins , Amy Morton , Elias Koteas , Jon Seda , Sophia Bush , Tracy Spiridakos , Brian Geraghty , Lisseth Chavez , Archie Kao .