The Obsession (S05E09)

Corrigan and Stacy respond to a minor complaint about a car parked illegally, but their day takes a dangerous turn when they discover an armed robbery in progress at a check-cashing store. As Corrigan calls for backup, Stacy bravely intervenes to prevent a shooting, only to find herself taken hostage by the trio of robbers. The leader of the group soon becomes fixated on Stacy, much to the annoyance of his girlfriend, who is also involved in the heist. While Hooker and Corrigan search for their missing partner, they face pressure from City Hall, where the father of one of the thieves has connections to the Mayor's re-election efforts, threatening to silence the case. Meanwhile, Stacy's life hangs in the balance as the leader's obsession with her grows, offering her a slim chance of survival.