The private investigator is one of the most enjoyable characters in the mystery genre, and one of the most enduring. Here, Matt Cost tackles nine questions that frequently arise around the PI.

What are the elements of a Private Investigator novel or movie?

First, you need a private investigator. This differs from a police detective and also from the amateur sleuth. A PI is somebody who works for themselves and gets paid to investigate a crime. The occurrence of a crime creates a criminal, thus an antagonist.

The base elements of a PI novel or movie, then, are quite simple. You need a PI, a crime, and an antagonist. There are various pieces that are helpful in building past this original foundation to create an engaging edifice of beauty and splendor. The setting is important, whether it be city, country, international, on an island or a boat; whatever the case, it is important for the author to build an authentic and scintillating backdrop. A wide array of suspects, often interspersed with red herrings, is a crucial ingredient in creating a story filled with flavors and spices. And, of course, some sort of resolution is needed, usually the solving of the crime.

What is the difference between a hard-boiled and a soft-boiled?

As in all things, there is no black and white distinction between hard-boiled and soft-boiled PI novels, but rather a wide array of shading. At the softer edge is the cozy, where the sleuth is usually an amateur in a small town trying to uncover a criminal amongst a generally happy population. Violence, language, and sex, for the most part, are kept off the pages and screen.

Taking a step toward soft-boiled, the PI may have become a professional, still lives in a small town, may have a pet for company, and occasional violence and language will pepper the story, and sex may be more evident as a building tension, but in no way graphic.

A bit further on the spectrum is hard-boiled, where you can expect gritty violence, cursing, and possibly graphic sex. The protagonist is often a loner in a big city with his or her own scale of ethics that determines the outcome. The PI has to battle against not only some sort of sordid organized crime, but a legal system that is every bit as corrupt.

What are the origins of the PI in fiction?

A disclaimer must first be made that this article will focus largely on the evolution of the Private Investigator in the United States. Many fine works have been created in Europe, Asia, and the world, but for the essence of space, we will restrict ourselves to the U.S.

In 1841, Edgar Allan Poe’s story, The Murders in the Rue Morgue, is published in Graham’s Lady’s and Gentleman’s Magazine. The story describes the extraordinary “analytical power” used by Monsieur C. Auguste Dupin to solve a series of murders in Paris. This is generally considered the birth of the Private Investigator.

Europeans would take the torch and run with it. Charles Felix and Wilkie Collins would vie for the spot of first private detective novel in The Notting Hill Mystery and The Moonstone, respectively. Sir Arthur Conan Doyle would give us Sherlock Holmes and Agatha Christie would bring us Hercule Poirot and Miss Marple. May more fine PIs would follow in Europe, but this article will stay on the west side of the Atlantic.

What are the first noir novels?

The “American Agatha Christie,” Mary Roberts Rinehart, possibly even more famous during her lifetime than her English counterpart, inspired many classic concepts of the PI, even if most of her stories involved amateur sleuths. She wrote in the traditional whodunnit style that would morph into the cozy in the late 20th century. The Circular Staircase of 1908 gave us the ‘had I but known’ school of mystery writing in which certain information is not correctly shared, driving the story forward and onward. Rinehart’s 1930 novel The Door is generally credited with originating the phrase, ‘the butler did it’.

The very first wisecracking, hard-boiled PI, Terry Mack, arrived on the scene in 1923, delivered to us by Carroll John Daly in the novel Three Gun Terry. While this may have been the first, the father of hard-boiled PI novels was right behind him with the Continental Op, an unnamed investigator for a detective agency in San Francisco from the mind of Dashiell Hammett.

Soon after the Continental Op, Hammett introduces us to perhaps the most famous PI of all time, Sam Spade, in the 1930 book, The Maltese Falcon. Spade would create the prototype for the PI, namely a detached demeanor, keen eye for detail, and unflinching determination to achieve his own justice, whatever that moral spectrum held. Humphry Bogart would soar Spade to new heights in the 1941 film of the same name that is generally considered to be one of the greatest movies of all time.

Hammett created another innovation in 1934 that has rarely been delved into since. In the Thin Man, he gives us Nick and Nora Charles, a bantering and romantically linked couple who solve mysteries together. This book would spawn a total of six Thin Man movies, as well as radio and television spinoffs. While this duo would lead to well-known tropes in many mediums, it is largely absent from most PI stories. Unfortunately for readers, WWII and an increasing fervor into politics linked to the communist party led Hammett into being blacklisted and ruined his writing career.

Raymond Chandler eased into being king of the hard-boiled PI novel with his 1939 publication of The Big Sleep featuring Philip Marlowe. Marlowe added a piece to the outwardly stoic PI, namely an inner self that was quietly contemplative and philosophical, even going so far as to enjoy chess and poetry. Unlike the solitary Spade novel, there would be seven full-length works devoted to Marlowe.

The blooming popularity of Chandler led him into screenwriting, his first venture being Double Indemnity, which he co-wrote with Billy Wilder. Bogart would also make Marlowe into a household name in the 1946 film, The Big Sleep. In all, there would be eleven adaptions into film from Chandler books.

Other major influences would be Ellery Queen, Erle Stanley Gardner’s Perry Mason, the Chinese American detective Charlie Chan from the pen of Earl Derr Biggers, and James Cain who gave us The Postman Always Rings Twice amongst many others. Ross Macdonald gave us Lew Archer, and Paul Newman brought him to life in Harper.

How are classic Noir PI novels related to modern PI stories?

Robert Parker’s Spenser would become the most prolific hard-boiled PI, starting in 1973 with The Godwulf Manuscript and continuing on for a total of forty novels, prior to Ace Atkins taking the reins and creating eight more to date so far. Spenser fit the mold set by Hammett and Chandler, going so far as to finish the final Marlowe book, Poodle Springs, that Chandler had completed only four chapters of before his death. His PhD dissertation, titled The Violent Hero, Wilderness Heritage and Urban Reality, discussed the exploits of fictional private-eye heroes created by Dashiell Hammett, Raymond Chandler, and Ross Macdonald.  

The Spenser novels diverged from those early pioneers of hard-boiled PI novels by inclusion of varied races and sexual persuasions within the pages. Gracing the pages are Hawk, an African American, and Chollo, a Mexican American, and Spenser’s Jewish girlfriend, Susan. Spencer’s closest friend in the police force is homicide detective Lieutenant Lee Farrell, who is openly gay. This inclusion makes Robert Parker the perfect bridge from the original noir PI to the modern writers of PI fame.

What are examples of Private Investigator TV shows and Movies?

Roman Polansky’s last film made in the U.S. was the neo-noir Chinatown starring Jack Nicholson as PI Jake Gittes. Polansky, cynical and dark after the recent death of his wife, Sharon Tate, paints a canvas of the misanthropic 1970s with broad strokes. Nicholson plays the classic noir PI with his own sense of justice to perfection, and the 1937 setting fits into the mold of the noir golden age.

Moving into lighter territory would be the Rockford Files. Jim Rockford is a pardoned convict of San Quentin prison who works as a PI out of his mobile home in a parking lot in Malibu. Contrary to the hard-boiled PIs, Rockford prefers to avoid fisticuffs and doesn’t like carrying his pistol. He does have his own moral compass that he tries to practice, and tongue-in-cheek humor peppers the many episodes.

Reminiscent of the wealth of Nick and Nora Charles, the 1980s would bring Thomas Magnum in Magnum PI, who lives on a luxurious estate in Hawaii. Reveling in the decadence of the decade, Magnum drives a Ferrari, only works when he wants to, and is surrounded by beautiful women. Contrary to the sharp suits of the noir PIs, Magnum paraded forth in Aloha shirts, a Detroit Tigers baseball cap, and sported a thick mustache.

Who are some of the greatest modern female PI authors?

In 1977, Marcia Muller would publish Edwin of the Iron Shoes, bringing us the first hard-boiled female detective, Sharon McCone. McCone down-to-earth, savvy, and as tough as any of her male counterparts in the hard-boiled genre. In a time when strong women were struggling to gain recognition, McCone made her mark as a kick-ass protagonist.

With Indemnity Only, Sara Paretsky takes the ground-breaking role of Muller a step further in creating a female PI who is every bit as hard-nosed as any man out there. V.I. Warshawski is a believable investigator with grit and the smarts in a genre in which women were typically either vamps or victims. V.I. lives in an apartment overlooking Wrigley Field in Chicago, drives an old gas guzzling car, and her only weakness seems to be for the red shoes she so loves. Her latest book, Dead Land, is considered one of the best mystery books of 2020.

Sue Grafton spent the first fifteen years of her writing career writing screenplays for television movies before beginning her alphabet series with A is for Alibi. Screenwriting taught her the structure, while a bitter divorce created the fantasies of different ways people could be killed. Kinsey Millhone, the protagonist, is the typical hard-boiled PI, former policewoman turned independent, and a loner at heart.

What are some of the hard-boiled PIs of the modern era?

With the publication of The Monkey’s Raincoat in 1987, Robert Crais introduces us to a PI who is every bit as tough as Spade, Marlowe, and Spenser, but also has a Mickey Mouse phone, a Pinocchio wall clock, quotes Jimmy Cricket, and wants to be Peter Pan. Elvis Cole is a tough, wisecracking, ex-Ranger, with an undeniable urge to do the morally right thing.

In 1986, at the age of thirty-four, Walter Mosely began his writing career. He has written every day since. His initial novel, Devil in a Blue Dress, published four years later, gave us one of the most iconic PIs of all time. Inspired by Hammett and Chandler, Mosely sets his protagonist, Easy Rawlins, into 1948 LA in the Watts area. Denzel Washington would bring Easy Rawlins into the mainstream in the middle of the decade in the film of the same name. The newest installment in the series, Blood Grove, is due out this year.

What is the future of the PI novel?

There will always be a place for the quiet, charismatic loner, who strides through the streets of our cities and metes out justice from a scale carried within their own pocket, but as surely as the world changes every day, that protagonist is also changing. They still have to crawl into the gutters and trashcans of their suspects, but now have to be aware of race, gender identity, politics, and the power of money. It is much more difficult to navigate a moral code in a world in which things are no longer black and white.