Season 4 Episode 7
The State Attorney's office calls upon the Intelligence Unit after the only witness in a serial rape case is murdered; Peter Stone offers Antonio a surprising - and tempting - opportunity.
Season 4 Episode 8
"A Shot Heard Round the World"
The police force is shaken after one of its own is targeted by a cop killer; Voight and team put everything on hold to identify the perpetrator from a long list of suspects and stop his violent rampage.