Philip Kerr's untimely death last year at the age of 62 deprived us of a gifted writer of a variety of books, from children's to non-fiction. But it was his creation Bernie Gunther, a sardonic cop and private investigator in Nazi Berlin, that captured the imagination of fans across the world. Gunther first appeared in 1989's March Violets, as an ex-policeman specialising in what Dashiell Hammett called "wandering daughter jobs" around the time of the 1936 Berlin Olympics. The original Berlin trilogy took us to the end of the war; after that Kerr had fun plunging readers forward into Gunther's postwar career in Cuba and back into the Nazi era.Metropolis, the last Gunther novel, begins in 1928 with Gunther working in the Berlin police vice department and lodging with four wonderfully drawn Christopher Isherwood types, including a writer and a musician/escort. A veteran of the Great War, Gunther is the perfect world-weary investigator for the glittering, doomed demi-monde of Weimar Berlin. As Metropolis opens, he is newly promoted to the murder squad of the Kriminalpolizei and begins investigating the serial murders of four suspected prostitutes. In a brilliant set piece scene deploying all Kerr's empathy and intelligence, Gunther enters into an imaginary dialogue with Mathilde Luz, a young Jewish factory worker who was the first victim.Nazis in the department wonder why Gunther cares so much about one dead Jewish girl - and of course within a decade a million Jewish children will be murdered under the Nazi racial laws. But nowhere in the series does Gunther commit the fallacy of thinking numerically about moral facts, and in a universe spiralling towards chaos his desire to establish a little local order in a sea of entropy is the best that he can do.When the daughter of a local crime boss is killed, the stakes are raised - and then someone starts murdering disabled veterans, as if wanting to purge Berlin of ugly reminders of a more complicated past, just as a bold tomorrow begins to gather strength. Wonderfully plotted, with elegant prose, witty dialogue, homages to German Expressionism and a strong emotional charge, this is a bittersweet ending to a superb series.