I don't read very much hard-boiled detective fiction, but I have read enough to know that the genre is a type of horror fiction, and like all horror, is based on goodness and order being attacked by evil and chaos.
A fine example of this is John D. MacDonald's 1979 novel, The Green Ripper, a book I read only because Stephen King praised it. A horror writer praising a detective novel about MacDonald's famous anti-hero, Travis McGee? It made me curious.
It turns out King was right in his assessment. Like all very good writers, MacDonald has a great understanding of human nature, which sometimes is not such a great thing. In the case of The Green Ripper the human nature that McDonald writes about is the mind of the political terrorist. If you want to understand that mind, this is the novel to read.
I had not read anything by MacDonald before, although I have heard of McGee. McGee is one in a long line of those loner/heroes who do what little they can to put things right. McGee calls it "doing my little knight-like thing." Such a character is brother to Robin Hood, the Scarlet Pimpernel, Zorro, and F. Paul Wilson's Repairman Jack.
I'm not giving anything away here, since it's on the cover of the book, but the plot concerns the murder of the only love of McGee life. McGee, just like every one of his kind from Edmond Dantes to Gully Foyle, hunts down those responsible for his loss.
The question, as it always is in cases like these, is if McGee seeks vengeance or justice. Men like McGee, and those like him, have a moral code they are actually willing to enforce. They don't make their own laws; indeed, although it's always unstated, they believe in Natural Law, most especially the one about "do not murder." And they are willing to personally deal out a great deal of violence, death and destruction to the guilty parties.
Are people like McGee what happens when they seek justice (or revenge) instead of allowing the government to do it? Or are they created because the government fails in its responsibility to enforce justice? These characters touch a nerve in people, and have for hundreds of years, ever since the modern novel was created. Clearly, there is a need for them. My view is these are the characters who do justice when the government fails in its job.
At first I used to read a great deal of science fiction, which is about, if anything, what is called "the sense of wonder." In a sentence, it can be described as "I want to live like that." It's a combination of admiration and envy. Horror fiction is just the opposite: "I do not want to live like that. Maybe I don't have the perfect life, but at least I don't have vampires after me."
Hard-boiled detective fiction, being horror fiction, is also about "I don't want to live like that." But there is more. Certainly the reader doesn't want to have the life described, but there is a part of them that says, "I sympathize with what he is doing, indeed support him fully in it." Even though it involves all kinds of mayhem and multiple deaths (of the guilty), there is a part of the reader saying, "You go! You go!"
And "go" is exactly what McGee does. And in his search for the killers he discovers exactly what makes political terrorists tick. It has, I have to point out, nothing to do with "they hate us for our goodness" or "they attacked us because we are good and they are evil." Such a view is extraordinarily naive. If anything, those views describe what what terrorists think of those attacking them.
Terrorists all are marginal, ostracized people, or at least think they are, which is essentially the same thing. They see things as either good or bad, black or white, with nothing in-between. Of course, they see themselves as good, which is why they are paranoid about people hating them "for their goodness." They are Utopians and idealists. As such, they believe in destroying society so a new, better one can arise. Who they destroy in the process is irrelevant; they are necessary sacrifices. Ultimately, all terrorists are Utopians. Perhaps all Utopians and idealists are in some degree terrorists.
The novel is relevant today because we are stuck in a war between two blind, fanatical Utopian groups wanting to destroy the other so they can impose their views on other people. Both ultimately are terrorists, even though they call themselves benefactors. They are an extraordinarily small group of people attempting to wreak havoc in the world.
MacDonald opens the book with a quote from Santanya that is always relevant, especially today: "Fanaticism is described as redoubling your effort when you've forgotten your aim." Idealists and Utopians, being fanatics, are always redoubling their efforts because they, too, always forget their aims.