St Agnes is the patron saint of chastity, engaged couples, rape victims, and virgins. So when Agnes repents and changes her ways, her decision leads her to her own end.
A serial killer is targeting women attending church because they are easy and trusting targets. Their faith makes them the perfect victims and he tortures them for hours. The police have no leads. The public are losing hope. When Agnes is murdered, Detective Black does not blame the killer. She blames God and his callous inaction.