In responding to a call Atwater and Burgess discover a gunshot victim and the only witness is Lexi Olinsky (guest star Alina Taber). The shooting is tied to a Latin gang.
To protect Olinsky’s daughter, Voight takes the case from the Gang Unit. Ruzek pulls up Burgess to help with an undercover mission that he hopes will help solve the case.
NBC has released the promotional photos for "Material Witness", check out all 9 stills in the gallery below: