Plain Jane, by Cristyn West:

Gritty and effective page-turner of a thriller with the serial killer being triggered by a “type”; in this case, the “plain Jane” brunettes of the title. I was hooked from chapter one, as the killer stalks a potential victim through the city at night, and they pass a crowd gathering outside a cinema showing a rerun of The Rocky Horror Picture Show, the fans of the movie, dressed in-costume for the event, unaware of the real horror in their midst.
There is an added dynamic with the sub-plot of the romance between criminal profiler and his ex, Nicole, a cop working on the case with him. The characters are well written and the story speeds along nicely with chapters and narrative passages that come as swift and sharp as a punch. This is a nice mix of tough cop thriller, drama, love story, gory scenes of murder, that come together in a hard-hitting, intelligently written story, with a current of dark humor flowing throughout.