Last time I went to the mystery bookstore looking for something hard-boiled, I came out with A Philosophical Investigation (Doubleday) tucked under my arm. I have since returned to seek out author Philip Kerr's previous novels, the Berlin Noir trilogy set in Nazi Germany, but A Philosophical Investigation is easily his best to date. In it, Kerr takes us to London in 2013, to a world where serial killings are rampant and scientific rationalism guides law enforcement and criminals alike. Named for the Victorian criminologist who posited a relationship between anatomical features and criminality, the Lombroso program uses DNA testing to detect aggressive personality disorders in men. Those whose results reveal a propensity to commit violent crime are enrolled in the state-run program under code names. A killer known only as "Wittgenstein" systematically begins knocking off Lombroso members, first Charles Dickens, next Bertrand Russell, working his way through a highly confidential list. Enter Inspector Isadora Jacowicz, New Scotland Yard's toughest. Struggling to control her own pugnacity, Jake engages in a dialogue on the ethics of crime and punishment with her quarry. Passages from Wittgenstein's journal and excerpts from philosophical tracts provide the framework within which the debate must find its conclusion. Cool, scary and very smart, Philip Kerr observes and respects the conventions of the "noir" while simultaneously mocking them. Recommended to anyone seeking an intellectually satisfying read.