In flashback, we discover Bianca and Harry shared a bit of nakedness back in the day, and she helped him out once when the High Council was pursuing him after the death of his uncle. Someone's trying to kill her, and she wants Harry to find out who.
As the plot unwinds, we discover more about the High Council as well as the organization of the vampire underworld in Chicago. A few hints are also dropped about Harry's past, during the flashbacks with Bianca. Although it appears Bianca might be the target of the High Council, in the end it turns out she's been set up by her protege/lover Natalie, who's trying to corner the local market of Third Eye, an undead-specific rage enhancing drug favored by portions of the vampire community.
Overall, another strong episode. I had a few quibbles--the bit where Bianca is accidentally dosed with Third Eye seemed contrived to me. Also, I'm pretty sure I remember Third Eye being a different sort of drug in the books--one that enabled non-magical folks to experience paranormal phenomenon. It seems odd to me to just reassign the name to a completely different drug, especially since the book-type Third Eye could be a great catalyst for TV episodes in the future. It seems like they could have used a different name that fit the vampire drug a bit better.
In any case, the show seems to be falling into a good groove. And is it just me, or is Harry just getting hotter and hotter?