The subtitle is The Testament of a Serial Killer. The novel is a scorcher. It is written in the form of an essay by convicted serial killer Graham Underwood, in which Underwood attempts to justify his murders. He challenges the morality of society as a whole using the currently popular equivalences (benefiting from a capitalist economy is the same as ordering the deaths of slave workers, and so on) and sophistry, and then goes on to explain why his work was actually a benefit to society since he was ridding it of worthless scum. He describes the British underclass in horrifying (and all too accurate) terms, well enough that the reader almost sympathizes with his anger.
The book reduces to absurdity the popular social philosophy idiocies and attacks the horrible effects these have had on people, using a sort of backwards approach perhaps better known in The Screwtape Letters. Unfortunately, it isn't a pleasant book to read, despite Dalrymple's notable skill with the language.