S3, E21: An apartment fire linked to a case of rape and attempted murder calls for members of the CPD to team with the Special Victims Unit, which had a similar unresolved case that has eluded them for more than 10 years. This prompts Sgt. Benson (Mariska Hargitay) to come in from New York to assist with the investigation in which she is all too familiar. Meanwhile, doubts among the squad towards one of their own causes Severide (Taylor Kinney) to lay down the law and Dawson (Monica Raymund) puts her life on the line during a call.