Sixth in the books series of medical examiner Maura Isles and Boston city police detective Jane Rizzoli.

A few years back I joined an obscure little whodunit book club that gave us books to read just so we could rate them. Nice work if you can get it, and I did. For a person such as  I, who couldn’t keep myself in books, this was ideal. Oh yes, there were some kumquats to gnaw through, but for the most part, I had, to one degree or another, a pretty good book to read when I was ready to relax in the evening. There were the exceptions to those kumquats too. One such non-kumquat was author Tess Gerritsen.

Fast forward to the present and Ms. Gerritsen's sixth in her series of books featuring heroines Laura Isles and Jane Rizzoli. All the books in this series are stand-alone thrillers, as is The Mephisto Club. The title refers to a somewhat loosely knit organization of wealthy but naive idealists who claim to seek out evil and try to strike it down. Or at least, so they say.

The club’s acolytes devote themselves to the study and analysis of evil: is it able to be explained by science? And does it have an absolute physical presence? Do modern day demons walk the earth? Drawing on a wealth of dark historical data and mysterious religious symbology, the club's scholars claim they can prove what they believe to be true -- that Satan and his minions actually exist among us today. But is the club only investigating murders, or are they the target of the killings? Or do they emanate from it?

As the story opens, Medical examiner Maura Isles and Boston City police detective Jane Rizzoli find themselves involved in an unnerving Christmas Eve investigation. A murder in a rundown house in the city -- a young woman, Lori Anne Tucker brutally murdered and then meticulously dismembered by her killer. The words "I have sinned", written in blood, are left ominously scrawled above her on the wall, along with what seem to be religious symbols. This whole murder scene, the women feel, is one of the worst they’ve encountered over the course of their careers. How were they to know this was only the beginning?