Fictional characters who work together in one capacity or another to solve a mystery have been a staple of the crime-fiction genre since Edgar Allan Poe wrote the first detective story in the early 1840s. Such characters may be amateur or professional or a combination of the two; of either gender; of any sort of ethnic, religious, or social background; and of any period in history. They need not function as equal partners in order to qualify, for the umbrella designation of “detective duos” is a broad one. Indeed, there are almost as many types and variations of sleuthing partnerships as there are types and variations of mystery and detective fiction itself.

The first and most influential type is that in which the celebrated cases of a master detective are chronicled by a close friend or relative who is either present during the investigation or provided ex post facto with all the details necessary to the case's solution. In this kind of story, the narrator generally contributes little or nothing to the solution, although he (for they're usually male) may be allowed to say or do something that triggers his idol's ratiocinative powers. Hence, critic H. R. F. Keating's term “trailing-behind narrator” for the passive member of the team. Despite his nonparticipant role, the narrator's presence is important for several reasons: He functions as a camera for the setting of scene, the establishment of the dramatis personae, and the noting of clues; he serves as a sounding board for the musings of the detective; the telling of the story from his viewpoint permits the inner workings of the detective's mind to remain a tantalizing mystery; and the relative shallowness of his own thoughts, plus his eagerness to extol the other's virtues (the trailing-behind narrator is usually a self-effacing individual), makes the sleuth seem all that much more clever, wise, and imposing.

Poe's 1841 tale, “The Murders in the Rue Morgue,” was both the first detective story and the first to feature such a duo. The master detective is, of course, C. Auguste Dupin; the narrator of this and the four other Dupin stories is so dwarfed by the Parisian sleuth's virtuosity that Poe did not even bother to provide him with a name. Though this method of detective storytelling was copied by other writers in the United States, chiefly the perpetrators of dime novels and story-paper weeklies, and by writers in England and France, it was not until British physician Arthur Conan Doyle penned the first Dr. Watson-narrated Sherlock Holmes story, A Study in Scarlet, in 1887 that the form achieved its highest level of excellence.

Aside from the unique character and deductive prowess of Holmes, the element that made the series the most popular and most imitated in the genre's history is Doyle's handling of Dr. John Watson. No trailing-behind cipher is he. Even though Watson is content to bask in Holmes' shadow, he is every bit as real and engaging a personage, and his friendship with the Great Man has a depth of feeling unlike that of any other nineteenth—and few twentieth—century detecting teams. Watson's eye is far keener than that of any of his counterparts; when he reports, often with journalistic precision, on the sights, sounds, and smells of London and the English countryside, we feel as if we have been transported back in time to that fascinating Victorian era.

Only a few of the many Holmes-Watson imitations and variations are of sufficient quality to have endured. The earliest and best of the strict pastiches are Arthur Morrison's tales of Martin Hewitt, a blander version of Holmes, which are narrated by his friend, the journalist Brett; the adventures originally appeared in The Strand Magazine, just as the Holmes-Watson stories did, and were first collected in Martin Hewitt, Investigator (1894). The most effective of this century's pastiches are the Solar Pons stories of August Derleth, begun in the late 1920s. They are not only faithful to the tone and spirit of Doyle's tales, but are likewise set in a well-depicted recreation of Holmes's and Watson's gas-lit London; Pons and his companion, Dr. Lyndon Parker, reside at 7B Praed Street and undertake to solve mysteries reminiscent in plot and even title (“The Adventure of the Limping Man,” “The Adventure of the Sotheby Salesman”) of the originals. Eleven collections of Solar Pons stories, beginning with In Re: Sherlock Holmes, appeared between 1945 and 1973.

Among the more significant of the early variations is E. W. Hornung's A. J. Raffles, gentleman, cricketeer, and notorious thief, who also sometimes functions as a sleuth and whose exploits are narrated in fawning style by his former school chum Bunny Manders. The popularity of such Raffles collections as The Amateur Cracksman (1899) led to several films, as well as a new series of Raffles and Bunny Manders tales by Barry Perowne that continued into the 1980s. Conan Doyle's success with Sherlock Holmes was one reason Hornung chose to emulate him; another was the fact that he was Doyle's brother-in-law.

The Red Thumb Mark, the first of R. Austin Freeman's stories about Dr. John Thorndyke, the most accomplished of the “scientific detectives,” and his chronicler, Dr. Christopher Jervis, appeared in 1907. In 1918, Melville Davisson Post published Uncle Abner: Master of Mysteries, called by author and editor Ellery Queen “the finest book of detective short stories written by an American author since Poe.” Uncle Abner is “a grimly austere and supremely righteous countryman who smites wrongdoers and mends destinies like a biblical prophet transplanted to the New World,” in another critic's description; his detections, set in rural West Virginia in the mid-nineteenth century, are narrated by his nephew, Martin, though Martin's role in some stories in quite minor.

Madame Rosika Storey and her secretary and chronicler, Bella, were the first important two-woman detective duo; they debuted in Hulbert Footner's 1926 collection, Madame Storey. Nero Wolfe and Archie Goodwin, Rex Stout's extraordinary team of private investigators, immediately made their mark in Fer-de-Lance (1934). Although Archie serves as narrator of Wolfe's deductive triumphs he also plays an active role in their cases and is portrayed in greater depth—and not incidentally treats the master detective with far less reverence—than any other narrator-partner. Lillian de la Torre's Dr. Sam: Johnson, Detector (1946) features the eighteenth-century lexicographer and sage in a series of tales narrated by his real-life biographer, James Boswell. Boswell's journals and his personal relationship with Dr. Johnson were surely influences on both Poe and Doyle in the choice of format for their detective stories, and in Lillian de la Torre's capable hands they made fitting detective-story heroes in their own right.

William MacHarg's Detective O'Malley, known as “the smartest dumb cop in detective fiction,” was introduced in 1930 in a series of Collier's short-shorts narrated by MacHarg himself. A collection of these, The Affairs of O'Malley, was published in 1940. Yet another variation was the long-running series of novels by Aaron Marc Stein writing as George Bagby, which began with Murder at the Piano (1935) and feature Inspector Schmidt, Chief of Manhattan's Homicide Squad, and his “Watson,” Bagby, whom a publisher allegedly assigned to travel with Schmidt and then write a book about his career. A second Stein series likewise makes use of the Holmes-Watson formula: Manhattan District Attorney Jeremiah X. Gibson and his coworker and friendly chronicler, Mac, partners-in-crime in eighteen books published under the pseudonym Hampton Stone. The first of these, The Corpse in the Corner Saloon, appeared in 1948.

Another popular type of detecting duo is the husband-and-wife team. The earliest of significance was an amusing pair of detective-agency owners, Tommy and Tuppence Beresford, who debuted in Agatha Christie's The Secret Adversary (1922). Two other Tommy-and-Tuppence novels were published, N or M? (1941) and Postern of Fate (1973), and a collection of their short cases, Partners in Crime, appeared in 1929. The first notable American married duo was Dashiell Hammett's Nick and Nora Charles; despite the fact that they starred in only one novel, The Thin Man (1934), the film version of the book (starring William Powell and Myrna Loy) and its five sequels established a lasting niche for the pair in American popular culture.

Patrick Quentin's Peter and Iris Duluth, a New York theater couple who detect in six novels, were the next major husband-and-wife team; their career debuted with A Puzzle for Fools (1936). Frances and Richard Lockridge's Pam and Jerry North started their extremely successful detective partnership four years later, in The Norths Meet Murder. Kelley Roos's Jeff and Haila Troy also began detecting in 1940, in Made Up to Kill; and in 1941 Frances Crane created the first of her color-titled Pat and Jean Abbott mysteries, The Turquoise Shop. The Norths and Troys do most of their sleuthing in New York City and environs; the Duluths traveled wider afield, to California and Mexico, for example, while the Abbotts are a globe-trotting pair whose cases occur in such exotic locales as Tangier and Hong Kong, as well as in various U.S. and European cities. Typical of all four series is bright, witty dialogue, mostly bloodless murders, and breathless chases during which the wife is placed at considerable peril. Only the Duluths were allowed on occasion to depart from the light-and-breezy formula, with the realistic introduction of personal and marital problems.

Four major husband-and-wife series were established in the 1970s and 1980s. The first two are Victorian-era historicals. Elizabeth Peters's archeological mysteries, set in both England and Egypt, feature Amelia Peabody and Radcliffe Emerson, colleagues who first meet in Crocodile on the Sandbank (1975) and later marry. The archeological backgrounds in each title are authentic in every detail, for like her duo, Peters has a Ph.D. in the field. Anne Perry's novels set in late-nineteenth-century England, begun with The Cater Street Hangman (1979), carry on the detections of Charlotte Pitt and her husband, Inspector (later Superintendent) Thomas Pitt. The Pitts are an odd couple, she a gentlewoman whose family considers her marriage beneath her and he a no-nonsense, hardworking police officer. The background differences between the two characters allow Perry to explore class and social issues of the period.

The husband-and-wife formula is also fully adaptable to the modern milieu, as proven by Herbert Resnicow's Norma and Alexander Gold. Born in The Gold Solution (1983), they were the first Jewish detecting couple—a sort of married version of Nero Wolfe and Archie Goodwin in that the husband is sedentary as the result of a heart attack and the wife does his legwork. A second Jewish team, Faye Kellerman's Peter Decker and Rina Lazarus, were unmarried when they debuted in The Ritual Bath (1985) and took their vows only after sharing three cases. Their partnership, like that of Anne Perry's Charlotte and Thomas Pitt, is one of a professional detective—Decker is a member of the Los Angeles Police Department—working in tandem with an amateur sleuth. Kellerman's depiction of this sort of relationship, and of the world of Orthodox Judaism, is particularly good.

The partnership of a police professional and an amateur is not limited to husband and wife (or unmarried lovers), of course. The earliest example of this type of pairing is Anna Katharine Green's That Affair Next Door (1897), in which elderly Miss Amelia Butterworth is teamed with New York policeman Ebenezer Gryce. This combination of nosy spinster and methodical law officer served as a prototype for numerous other detecting duos, most prominently Stuart Palmer's Hildegarde Withers and Inspector Oscar Piper. The Notorious Sophie Lang (1925) by Frederick Irving Anderson brought together detective-story writer Oliver Armiston and Deputy Parr of the New York police, who are also featured in a collection of eight excellent short stories, The Book of Murder (1930). Other professional-and-amateur duos include Inspector Arnold of Scotland Yard and his friend, avocational criminologist Desmond Merrion, who star in more than sixty novels by Miles Burton (Cecil John Charles Street) published between 1931 (The Secret of High Eldersham) and 1960 (Legacy of Death)

The fact that actual police officers often work in pairs has led to several fictional duos whose cases tend to be much more realistic than those in which the police enlist the aid of an amateur. One of the best known professional partnerships is that of black Pasadena, California, plainclothesman Virgil Tibbs and white Carolina police chief Bill Gillespie; John Ball's 1965 novel, In the Heat of the Night, explores serious racial issues set against the background of a murder investigation in a small Southern town and was the inspiration for the 1967 film of the same title, starring Sidney Poitier and Rod Steiger, as well as the episodic television series featuring Carroll O'Connor and Howard Rollins. (In both film and TV versions Tibbs's homebase became Philadelphia, and the small Southern town was relocated to Mississippi and renamed from Wells to Sparta.) Carolyn Weston's three-book series featuring the Santa Monica Police Department's investigative team of Casey Kellog and Al Krug, introduced in Poor, Poor Ophelia (1972), are not nearly as well known as the television show that was based on the series—The Streets of San Francisco, starring Karl Malden and Michael Douglas—but they stand on their own as incisive studies of the relationship between partners separated by the generation gap. The same is true of Reginald Hill's excellent series about Yorkshire, England's Superintendent Andrew Dalziel and Sergeant Peter Pascoe, who were inaugurated in A Clubbable Woman (1970).

Peter Lovesey's novels featuring Sergeant Cribb and Constable Thackeray of Scotland Yard's Criminal Investigation Department, which began with Wobble to Death (1970), combine the procedural with the historical tale; each illuminate some aspect of Victorian England, such as the popular stage or marathon racing. James McClure created an unusual duo, the South African team of Lieutenant Tromp Kramer of the Trekkersburg Murder and Robbery Squad and his Bantu assistant, Detective Sergeant Mickey Zondi, in The Steam Pig (1971); the pair battle the specter of apartheid as well as criminal elements in six additional novels. A Choice of Crimes (1980) by Leslie Egan (a pseudonym of Elizabeth Linington) brings together yet another pair who would eventually marry: Vic Varallo and Delia Riordan of the Glendale, California, police force. The Varallo-Riordan books provide solid insight into what life is like for both a policewoman and two-officer family.

The most popular of the current professional teams is also a duo in which both partners are ethnic. Tony Hillerman began his fine series about the Navajo Tribal Police by focusing on a single, seasoned officer, Lieutenant Joe Leaphorn, in The Blessing Way (1970); in People of Darkness (1980), he introduced a second series character, Sergeant Jim Chee, who is much younger and less disillusioned than Leaphorn; and in the 1987 novel Skinwalkers, he brought the pair together with considerable success. The contrasts between the older man, who has lost his faith in the traditional Native American ways, and the younger one, studying to become a shaman, reveal the inner conflicts of a culture that has been damaged by encroachments from the outside and feels a desperate need to preserve its customs.

A similar study in contrasts is that of an earlier pairing of men of different ethnic and religious backgrounds, Roman Catholic priest Father Joseph Shanley and Jewish Detective-Sergeant Sammy Golden; Jack Webb's nine-novel series featuring this affecting duo commenced with The Big Sin (1952). A few years after the Shanley-Golden duo appeared, the first team of African-American detectives was created by mainstream black novelist Chester Himes in For Love of Imabelle (1957): tough and violent Harlem policemen Coffin Ed Johnson and Grave Digger Jones. Himes knew whereof he wrote, having lived in Harlem and having spent seven years in prison, yet he finally ended the series after a seventh title, Blind Man with a Pistol (1969), because, as he put it, “the violence shocks even me.”

A much less hard-boiled collaboration is Beyond the Grave (1986), in which Marcia Muller and Bill Pronzini combined two of their individual series characters, contemporary Hispanic museum curator Elena Oliverez and 1890s San Francisco-based private investigator John Quincannon, in a unique blend of the modern and the historical mystery; the story bridges a nearly hundred-year span of time, with Oliverez in 1986 resolving a partially unsolved 1894 case of Quincannon's through a combination of the private detective's case reports and her own legwork and deduction. Barbara D'Amato's half Hispanic, half Italian Chicago policewoman, Susannah (Suze) Maria Figueroa, teams with black officer Norm Bennis in the 1996 novel of high-tech crime, Killer.app. The engaging pair, who first appeared in a series of short stories, are highly entertaining and provide readers with a realistic look at day-to-day urban police work.

Until recent years, gay and lesbian detectives have been few and far between in crime fiction. The first duo to include a homosexual was introduced in 1980's Vermillion by Nathan Aldyne, a joint pseudonym of Michael McDowell and Dennis Schuetz; in this and three subsequent color-coded titles, gay bartender Dan Valentine and his straight woman friend, Clarisse Lovelace, joined forces to solve mysteries set in Boston and on Cape Cod. In the late 1980s Ellen Dearmore (a pseudonym of Erlene Hubly) combined the lesbian mystery with the historical mystery in a pair of novelettes featuring Gertrude Stein and Alice B. Toklas as crime-solvers and peopled with numerous other historical figures. The author's sudden death tragically ended plans for additional Stein-Toklas mysteries.

The various types and combinations of wholly amateur duos are wide-ranging, husband-and-wife teams being just one of many. E. Phillips Oppenheim introduced one of the more unusual pairings in A Pulpit in the Grill Room (1938): Milan hotel maître d' Louis, who solves mysteries from his table in the grill room with the aid of retired army officer and journalist Lyson. In the same year, married collaborators G. D. H. and Margaret Cole published a collection of short stories, Mrs. Warrender's Profession, in which the mother of their series sleuth, James Warrender, outdetects her professional son. James Yaffe's delightful series of “Mom” stories—two novels and numerous short tales, the best of which were collected in 1997 under the title My Mother, the Detective—are built along the same lines as the Coles' Mrs. Warrender.

Aaron Marc Stein's The Sun Is a Witness (1940) introduced archeological sleuths Tim Mulligan and Elsie Mae Hunt, colleagues and platonic friends who apply their understanding of history and nuances of various cultures to resolve mysteries in such far-flung and well-depicted locales as Mexico, Greece, and Yugoslavia. George Baxt, known for his novels about gay New York police detective Pharoah Love, began a second series in 1967's A Parade of Cockeyed Creatures, this one starring eccentric lovers and amateur detectives Sylvia Plotkin and Max Van Larsen. John D. MacDonald's immensely popular Travis McGee often detected with a partner, his economist friend, Meyer; McGee, whose self-described profession of “salvage consultant” hides a darker side to his work, enlists Meyer's aid in several titles, notably Darker Than Amber (1966). Another well-regarded amateur team, journalist Maggie Rome and cantankerous New England newspaper editor C. B. Greenfield, was established by Lucille Kallen in her 1979 novel, Introducing C. B. Greenfield. Though frequently at odds, the pair is always gruffly affectionate, with Rome doing most of the legwork and Greenfield applying his intellect to the information she gathers in order to bring about a solution.

The private-eye story is a subgenre typified by heroes who are loners. Nevertheless, a surprising number of fictional private investigators have worked with others in their profession, as well as with amateurs and members of different professions—a tradition that extends back to the dime novels of the nineteenth century and the tandem exploits of such characters as Old Sleuth and Young Sleuth, and Nick Carter. Carter, who detected with his father and a variety of other partners, was the most popular of all the dime-novel sleuths; first introduced to the American public in 1886, his career lasted through several incarnations, the last of them as a James Bondian secret agent, well into the 1980s.

Dime-novel detectives were in effect superheroes, possessing vast amounts of arcane knowledge, abnormal physical abilities, and a talent for assuming almost any identity and disguise. Much more realistic were the detectives who populated the offspring of the dime novels, the pulp-paper magazines that flourished during the first half of the twentieth century. Such upper-echelon titles as Black Mask, Dime Detective, Detective Fiction Weekly, and Street and Smith's Detective Story were training grounds for some of the more important names in the crime-fiction genre, among them Dashiell Hammett, Raymond Chandler, Erle Stanley Gardner, Cornell Woolrich, and Fredric Brown. The hard-edged stories that were the pulps' staple fare displayed a wide variety of series characters, including such private-eye duos as Roger Torrey's Marge Chalmers and Pat McCarthy; Merle Constiner's The Dean and his “Watson,” Ben Mathews; and D. L. Champion's Rex Sackler and Joey Graham. (Non-private-eye duos were also a mainstay of the pulps. Two of the best known are Erle Stanley Gardner's Ed Jenkins, the Phantom Crook, who is joined in many Black Mask stories by his wife, Helen Chadwick; and Frederick Nebel's Police Captain Steve McBride and alcoholic reporter Kennedy of the Free Press, who were likewise showcased in a long-running Black Mask series.)

The most famous private detective team is certainly Rex Stout's Nero Wolfe and Archie Goodwin. Almost as renowned in their day were Bertha Cool and Donald Lam, an unlikely pair of Los Angeles operatives; first seen in The Bigger They Come (1939), they were featured in another thirty novels over an equal number of years. Originally an underpaid assistant and later Bertha's partner, Lam does most of the active detecting because, we're told, private investigation is an unseemly profession for a woman. In fact, Bertha is a mountain of a woman who loves to watch Donald work and can seldom be moved by anything other than a large fee. Lam, on the other hand, is a former lawyer who knows “just how far he can stick his neck out … a romantic at heart, but hard as a diamond and a man who never forgets a favor or an injury.”

Geoffrey Homes (Daniel Mainwaring) launched the careers of chubby, unconventional Humphrey Campbell and his fat, lazy, and corrupt partner, Oscar Morgan, in Then There Were Three (1938) and brought them back in four more fast, furious, and witty mysteries set primarily in central California. Otis Beagle and Joe Peel, “two of the most upright and fearless heels ever to run a detective agency,” were the invention of former pulp writer Frank Gruber; the southern California-based partners starred in two novels, Beagle Scented Murder (1946) and The Lonesome Badger (1954). (Gruber's primary series also utilized a duo, Johnny Fletcher and his muscular stooge, Sam Cragg, itinerant book salesmen and amateur sleuths in The French Key, 1940, and a dozen subsequent novels.) Fredric Brown's Ed Hunter and his uncle, Am Hunter, joined forces in The Fabulous Clipjoint (1947) to investigate the murder of Ed's father, and worked so well together that they later opened a detective agency; their exploits are chronicled in a total of seven novels and one short story. New York City detective agency owners Schuyler Cole and Luke Speare, the protagonists of The Deadly Miss Ashley (1950) and five other novels by Frederick C. Davis, are an appealing pair whose cases' solutions, like those of the Hunters, depend far more on legwork and deduction than on the violent tactics utilized by so many fictional private eyes.

Examples of investigators joining forces with police officers, lawyers, and other professional and nonprofessional individuals are more numerous. Erle Stanley Gardner's Paul Drake detected with attorney Perry Mason in many novels, such as The Case of the Moth-Eaten Mink (1952), as well as in the original Perry Mason television show (1957-1966) starring Raymond Burr, William Hopper, and Barbara Hale. Thomas B. Dewey's series of paperback originals featuring Los Angeles investigator Pete Schofield and his sultry wife, Jeannie, is one of the few examples of a husband-and-wife duo in which one of the team is a private eye; the series began with Go to Sleep, Jeannie (1959) and continued through seven additional novels. Marvin Kaye's series about publicist Hilary Quayle and private operative Gene (a man so colorless that Kaye did not see fit to give him a last name) is a variation on the theme in that Hilary would rather be a private detective, but feels she would have difficulty succeeding because of her gender. In the first of their adventures, A Lively Game of Death (1972), she thus coopts Gene to provide the proper legal umbrella under which she can operate. A similar rationale and ploy were used as the basis for the 1980s television series Remington Steele, starring Stephanie Zimbalist and Pierce Brosnan. A 1978 novel by Bill Pronzini and Collin Wilcox, Twospot, teamed the “Nameless Detective” and Lieutenant Frank Hastings of the San Francisco Police Department. Working together, the two professionals solve a complex series of crimes and narrowly avert a political assassination.

Easily the most offbeat pairing in this category is that of Norbert Davis's Doan and Carstairs, whose unique talents are displayed in three novels—The Mouse in the Mountain (1943), Sally's in the Alley (1943), and Oh Murderer Mine! (1946)—and two long pulp novelettes. Doan is a private eye who looks fat but isn't, and who, despite a great fondness for alcohol, has never suffered a hangover; Carstairs is an aloof, fawn-colored Great Dane whom Doan won in a crap game and who considers Doan a low, uncouth person, not at all the sort he would have chosen for a master. Their adventures are both hard-boiled and funny.

Fictional espionage agents, like private eyes, tend to be loners, but there are a number of duos of this type as well. The earliest are two young men from the British Foreign Office, Carruthers and Davies, who stumble across German plans to invade England in Erskine Childers' highly acclaimed novel The Riddle of the Sands (1903). John Buchan's British intelligence agent, Richard Hanny, is aided by the American agent Blenkiron in thwarting the Kaiser in Greenmantle (1916). Two operatives of an unnamed American intelligence organization, Harrigan and Hoeffler, help preserve national security in a series of tales by Patrick O'Malley (a pseudonym of Frank O'Rourke); the first of these, The Affair of the Red Mosaic, appeared in 1961.

Ross Thomas's The Cold War Swap (1966) teamed undercover agent McCorkle with an able amateur, Padillo; he brought them back for three encores, all set in Washington, D.C. Michael Gilbert's team of deadly British counterintelligence agents, Mr. Calder and Mr. Behrens, appears in numerous short stories. In perhaps the most unusual twist on a spy duo, Dorothy Dunnett's Johnson Johnson, skipper of the yacht Dolly, teams with a different woman (or “bird”) in each of six titles set in such locales as Scotland, Spain, and the Bahamas; the first of these, Dolly and the Singing Bird (U.S. title: The Photogenic Soprano), was published in 1968. All titles in the series originally appeared in England under the author's real name, Dorothy Halliday.

Yet another variation on the duo theme is the teaming of two authors and their individual series characters on common cases. Stuart Palmer's New York-based spinster schoolteacher, Hildegarde Withers, and Craig Rice's hard-drinking Chicago lawyer, John J. Malone, joined forces in six novelettes collected in People vs. Withers and Malone (1963). Richard S. Prather and Stephen Marlowe united their best-selling softcover private eyes, Shell Scott and Chester Drum, in the wild and woolly Double in Trouble (1959). In the only prominent two-author, two-gender pairing to date, Marcia Muller's Sharon McCone and Bill Pronzini's “Nameless Detective” shared a case in Double (1984) that takes place not in San Francisco, where both sleuths normally operate, but at a private-eye convention in San Diego.

Finally, there are the pairings of two different series characters created by one author. A few examples among many: Carter Brown's sheriff's investigator Al Wheeler and his flashy female private eye, Mavis Seidlitz, in Lament for a Lousy Lover (1960); Michael Innes' John Appleby of Scotland Yard and portrait artist and amateur sleuth Charles Honeybath, in Appleby and Honeybath (1983); and the aforementioned joining of Tony Hillerman's Navajo Tribal Policemen, Joe Leaphorn and Jim Chee.

Detecting duos have also been prominently featured in other forms of popular culture: films, radio and television shows, even comic books and comic strips. Such superhero teams as Superman (Clark Kent) and Lois Lane, Batman and Robin the Boy Wonder, The Green Hornet and his faithful valet, Kato, and The Shadow (Lamont Cranston) and Margo Lane certainly qualify. As do Sherlock Holmes and Dr. Watson as portrayed by Basil Rathbone and Nigel Bruce in numerous films; and such other cinematic pairs as Nick and Nora Charles, Charlie Chan and his Number One (or Number Two or Number Three) son, Hildegarde Withers and Oscar Piper, and Agatha Christie's Miss Marple and her friend Jimmy in the amusing trio of novel adaptations starring Margaret Rutherford (e.g., Murder at the Gallop, 1963). In addition, such celluloid sleuths as The Saint, The Falcon, Torchy Blane, Ellery Queen, The Crime Doctor, and Boston Blackie had recurring sidekicks and foils who both helped and hindered their investigations.

Among the more prominent radio series duos were George Harmon Coxe's Flashgun Casey and his girlfriend, Annie Williams (Casey, Crime Photographer); Havana charter boat owner Slate Shannon and his lady love, Sailor Duval (Bold Venture, starring Humphrey Bogart and Lauren Bacall); Mr. Keen and his intelligence-challenged sidekick, Mike Clancy (Mr. Keen, Tracer of Lost Persons); and Jack, Doc, and Reggie of the A-1 Detective Agency, technically a trio, though Jack and Doc did most of the investigating (I Love a Mystery). The list of television duos is even longer. In the 1950s there were Mr. and Mrs. North, starring Richard Denning and Barbara Britton, and Dragnet, in which Jack Webb's Sergeant Joe Friday of the Los Angeles Police Department worked with such partners as Frank Smith (Ben Alexander) and Bill Gannon (Harry Morgan). In the 1960s there were Kelly Robinson (Robert Culp) and Alexander Scott (Bill Cosby), the globe-trotting espionage agents in I Spy; Napoleon Solo (Robert Vaughan) and Illya Kuryakin (David McCallum), who battled the international crime syndicate THRUSH in The Man from U.N.C.L.E.; and private eye Joe Mannix (Mike Connors) and his African-American secretary, Peggy Fair (Gail Fisher), in Mannix. In the 1970s and 1980s there were San Francisco police commissioner Stuart McMillan (Rock Hudson) and his wife Sally (Susan St. James) in McMillan and Wife; San Francisco Police Lieutenant Mike Stone (Karl Malden) and Inspector Steve Keller (Michael Douglas) in The Streets of San Francisco; southern California-based amateur crimesolvers Jonathan and Jennifer Hart (Robert Wagner and Stephanie Powers) in Hart to Hart; and New York police officers Christine Cagney (Sharon Gless) and Mary Beth Lacey (Tyne Daly) in Cagney & Lacey.

The stories gathered in these pages cover most of the broad spectrum of detective duos, both in historical development and in types of partnerships. Edgar Allan Poe's “The Purloined Letter” is one of the first detective stories and also features the first example of a duo, that of the master detective and his chronicler. The selections by Sir Arthur Conan Doyle (Sherlock Holmes and Dr. Watson), R. Austin Freeman (Dr. John Thorndyke and Christopher Jervis), and Hulbert Footner (Madame Rosika Storey and Bella) are also examples of this type. Husband-and-wife teams are well represented by Frances and Richard Lockridge's Mr. and Mrs. North, Kelley Roos's Jeff and Haila Troy, and Patrick Quentin's Peter and Iris Duluth, as are pairs of male and female private investigators by P. G. Wodehouse's Paul Snyder and Elliot Oakes, Rex Stout's Nero Wolfe and Archie Goodwin, Fredric Brown's Ed and Am Hunter, and Marcia Muller's Sharon McCone and Rae Kelleher. And Bill Pronzini's Sabina Carpenter and John Quincannon story offers a look at both a two-gender and an 1890s private-eye duo. Barbara D'Amato's Suze Figueroa and Norm Bennis are police officers as well as ethnic detectives. Another ethnic pairing is Jack Webb's Father Joseph Shanley and Detective-Sergeant Sammy Golden. Agatha Christie's Mr. Satterthwaite and the mysterious Harley Quin may be classified as amateur sleuths, and Julie Smith's Skip Langdon and Steve Steinman are a police officer-amateur duo. There are forensic pathologists (Lawrence G. Blochman's Dr. Daniel Coffee and Dr. Motilal Mookerji, another ethnic character), Interpol agents (Edward D. Hoch's Sebastian Blue and Laura Charme), spies (Michael Gilbert's Mr. Calder and Mr. Behrens), and actual historical figures (Ellen Dearmore's Gertrude Stein and Alice B. Toklas). Also represented is the collaboration between two writers and their individual series characters (Stuart Palmer's Hildegarde Withers and Craig Rice's John J. Malone), and, just for fun, a detective association between an animal and a human (Lilian Jackson Braun's Siamese cat Phut Phat and one of its owners, known as Two).

These stories also cover a wide range of detective fiction types: pure deduction, impossible crime, cozy, dark comedy, espionage, procedural, historical. Their locales are likewise varied: England, Europe, Antarctica, and such U.S. settings as New York, Chicago, San Francisco, Los Angeles, and a pair of fast-moving trains—one heading from Chicago to New York and the other across California's Mojave Desert a hundred years ago.

Readers will note the absence of a story featuring any African American detective other than Barbara D'Amato's Norm Bennis. This is because no suitable work exists. Chester Himes' Harlem police detectives Coffin Ed Johnson and Grave Digger Jones appear only in novels, as do Ed Lacy's Touissant Moore and other individuals who detect alone; and while there are short stories featuring such notable black detectives as Walter Mosley's Easy Rawlins and Gar Anthony Haywood's Aaron Gunner, these characters also do not work with partners. Hawk, a featured player in Robert B. Parker's series of novels about Boston private eye Spenser, does not function in the capacity of a detective, or figure in the one Spenser short story.

Similarly, Tony Hillerman's Joe Leaphorn and Jim Chee, among other ethnic detectives, appear together in novels but no shorter work. The same is true of such famous non-ethnic duos cited in this introduction as Dashiell Hammett's Nick and Nora Charles, Erle Stanley Gardner's Perry Mason and Paul Drake, A. A. Fair's Bertha Cool and Donald Lam, Ross Thomas's McCorkle and Padillo, Anne Perry's Charlotte and Thomas Pitt, and Elizabeth Peters's Amelia Peabody and Radcliffe Emerson. Nor are there any short stories featuring a gay male duo (or a gay male and a heterosexual partner), nor any duo stories by such best-selling crime-fiction writers as Patricia D. Cornwell, Sue Grafton, John Grisham, Elmore Leonard, and Sara Paretsky.

There are, of course, many detective partnerships past and present not mentioned in the preceding pages. Space limitations precluded the listing of every established series and individual novel, and at the present rate with which detective series are being inaugurated in the booming mystery fiction market, it is quite probable that more than one new detective duo will have been launched between the time these words are being written and their publication. The possible variations on the types of partnership sleuths, as we've endeavored to point out, are dependent only upon an author's—or team of authors'—ingenuity, and therefore are virtually infinite.