The Obsession - S5.E9

Corrigan and Stacy respond to a seemingly trivial call about an illegally parked vehicle, only to stumble onto an armed robbery of a check-cashing outlet. As Corrigan calls for back-up, Stacy intervenes in the robbery to stop a man from being shot, only to taken hostage by the trio of armed thieves. With Stacy held prisoner by the robbers, the head of the trio rapidly develops an ""obsession"" for her, much to the aggravation of his girl-friend, who is also one of the theives. As Hooker and Corrigan search for Stacy and the thieves, they risk taking on the might of City Hall when it becomes apparent that the father of one of the trio is involved in the Mayor's re-election campaign and is prepared to pull strings to keep the whole case quiet. Meanwhile, the trio's leader's obsession with Stacy continues to grow – and it is the only thing that is keeping her from being killed...