Filth - Irvine Welsh (1998)

There are two main characters in the book: Bruce Robertson and a worm living in his intestines, on whose behalf the narrative is also conducted. Bruce is a cynical, calculating, unscrupulous and corrupt policeman, promiscuous in sexual relations and regularly using drugs, who seeks to get the vacant position of detective inspector. He uses any methods to eliminate possible competitors. Along the way, he investigates the murder of a black youth.