McKenzie's Friend is a difficult book to categorise. Part crime, part comic fiction, it is the tale of understrapper Harry Fielding, "a bob-a-job man for the MI5", whose decision to retire from the business is interrupted by the arrival of an old friend. Alfie, crooked policeman and estranged husband of the delectable Ruth, lures a reluctant Fielding into one more case involving the disappearance of the daughter of a rich businessman. Fielding gets involved against his better judgment, and though cynical and worldweary, he surprises himself and the reader with his inspired and passionate defence of justice. There are moments of human insight and keen perception in here, but the book fails to maintain a clear focus. While the character of Henry Fielding is credible and humane, McKenzie's Friend meanders too much between genres to make the narrative compelling.