Let me just start off by saying that I don't read a lot of mystery/thrillers. However, it seems to me that one of the conventions of the genre requires have some sort of cop/detective in a series of books that all stand-alone. (Unlike the fantasy genre in which all the books in a series need to be read in order.) When I'm browsing in the genre, I sometimes get confused as to who the writer is and who the detective is. In the case of "Vanish" by Tess Gerritsen, I think the story would have been better served to not have the series protagonists. The parts of the story told by Mila were horrific and compelling. The could have seriously stood alone in a novel or been told in juxtaposition to the story of one of the hostages at the hospital.
I found the series leads of Maura and Jane to be boring and cliched. They moved around the story in improbable ways and I never got a real sense of motivation from them. Despite my dislike of the lead characters, I did find the story very engaging and finished it in about a day. It kept me up late last night. I read the blurbs on some of Gerritsen's other books when I was in the bookstore and the premises sound interesting. I will probably read The Mephisto Club A Novel
because it sounds like a particularly interesting story and I really liked the excerpt that was printed at the end of this one. For a good story, I can overlook the weakness of the generic leads.