ASPLENDID debut, indeed, for John Douglas in Shawnee Alley Fire (St. Martin's, $15.95). Here certainly is a contender for the Edgar Award for best first mystery of this year. It is a mystery novel with genuine characters, a freshly observed scene, a sense of social history and a distinctive voice.

As the keynote for his novel, Douglas takes a quotation from Somerset Maugham's The Razor's Edge: "For men and women are not only themselves, they are also the region in which they were born, the city apartment or the farm in which they learned to walk, the games they played as children, the old wives' tales they overheard. . . . It is all these things that made them what they are and these are the things that you can't come to know by hearsay, you can only know them if you have lived them."

"A mystery of the Alleghenies" is the subtitle of Shawnee Alley Fire. And the landscape of the Appalachian mountain country is a central character, shaping people and events, making them what they are.

It is 1982, and the recession has hit Shawnee, an already depressed town of 40,000 in West Virginia, once a flourishing railroad hub and steel-plant center. It's hard times again, and 34-year-old Jack Reese returns to the hometown he had left 15 years earlier to make his living as a photographer. The freelance magazine market has dried up.

He sets up a studio in the old homestead (no rent). In the first section, Reese is the narrator. He tells how a young woman comes to the studio, asks him to take a passport photo, and then returns for two more photo-taking sessions, each more erotic and seductive than the last.

On the night she is to show up for the fourth session, there is a fire in Shawnee Alley behind Reese's house. Old Daniel, an 85-year-old neighbor, dies in the fire. A few days later the body of the mysterious woman is found in the town canal. She had been beaten to death.

What possible connection can there be between the two deaths -- one of a retired railroad man and the other (as it turns out when the body is identified) of the daughter-in-law of the town's wealthy and proud dowager? It is here that we meet Edward Harter, a police detective, who will dominate the story -- along with the Allegheny mountain country. Author Douglas deftly shifts between Reese's first-person narration and Harter's investigation, told in the third person.

Harter is a patient, dogged investigator. He finds links to the past with answers to the questions of how two old men from Wild Stream, W. Va., both died in fires and why a fundamentalist preacher acknowledges an anonymous gift "in memory of A.L." on the sign in front of his new academy.

"You can only know them if you have lived them," Maugham wrote. And Douglas, born in Cumberland, Md., "the queen city of the Alleghenies," and now living in West Virginia, knows of what he writes.

The mountain country is there, a brooding backdrop, with houses slanted into the hillsides, five steps below street level. People live in their kitchens, hang laundry on the line, eat tomato sandwiches in hard times and still make food a communal event with offers of coffee and poorman's cake. The dialogue rings true without being self-conscious ("I'll rise you up," says Reese's neighbor), and the language is intriguing (a publicity-seeking congressman is a "snollygoster.")

Shawnee Alley Fire is a haunting novel. You will remember the people -- May and Tattoo, Reese's neighbors, sturdy mountain folk with simple dignity; Harter, the decent, hardworking cop more complex than he appears on the surface; the minister who runs a soup kitchen for the poor while a charismatic preacher builds a handsome Christian academy; the old men with long memories of union battles and company thug scabs, of FDR and Eleanor.

Much like his photographer, Douglas captures "actions trapped in time and space" -- Appalachia of the 1920s and '30s and early '80s. His lean, spare prose reflects his mountain country and folk. "The lines were strip-mined into his face," he writes of old Daniel. This is an impressive debut.

Medieval Mystery

THE DEVOUT followers of Brother Cadfael, the Benedictine monk who performs miracles as an amateur sleuth in the medieval mysteries of Ellis Peters, are in good luck: The Rose Rent (Morrow, $15.95), the 13th chronicle in this charming series, finds the ex-Crusader at top form.

It is the late spring of 1142, and King Stephen and Empress Maud still are warring for the crown. Back at the abbey, Brother Cadfael is tending his herb garden and watching the first buds of the rose bushes swelling to break into bloom. It would be a sad day if there were no roses by the 22nd day of June. If so, the young Widow Perle would not get her rent -- one white rose -- for the gift of her house to benefit the Shrewsbury Abbey and the contract would be annulled.

But someone does not want the rent paid. Brother Eluric, a young monk who has been entrusted to deliver the rose rent for the last three years, is found knifed to death beside the hacked rose bush. Among the suspects are several suitors vying for the widow's hand and her patrimony.

If attentive readers are likely to spot the likely villain several chapters before Cadfael, it makes little difference. For the joys of the Peters mysteries lie in the telling -- the historical detail, the view of medieval life in town and monastery, the lively characterization and the author's graceful, literate prose.

One of the delightful moments in The Rose Rent comes when Abbot Radulfus gently cautions an overwrought young monk not to inflate his minor offenses into grave sins and not to seek extravagant punishment: "You are far from a saint -- so are we all -- but neither are you a notable sinner; nor, my child, will you ever be."

It is Cadfael who counsels the young Widow Perle not to be hasty about entering a nunnery since the religious life should be a passion not a refuge. An independent woman with a comfortable income, the Widow Perle is a far more interesting heroine than the fair-skinned young women with golden hair who appear in many of the earlier Cadfael novels. They invariably fall in love with handsome young men who turn out to be noblemen hiding out in humble disguise. The Widow Perle and her protector, a widower-bronzesmith, are of sterner stuff.

The Nun's Story

IF THERE ever was an odd couple it would be Harry Garnish, your standard fast-talking, boozing, womanizing private eye, and Bridget O'Toole, a sixtyish former nun and teacher who took over O'Toole Investigations, Inc., after her father's death. They form an unlikely team in Frank O'Connell's Blood Lake (Walker, $16.95).

Their second case (Murder Among Friends was the predecessor) takes a reluctant Harry from Chicago to a rustic lodge in the Wisconsin woods to check discreetly on a Mrs. Cheryl Howard for her husband. Sure enough Mrs. Howard arrives with a male companion. Soon both are found dead, and what started as a case of adultery turns into murder. Bridget arrives in a jogging suit to join Harry, and the two uncover a blackmail ring and other assorted crimes.

The unremittingly wisecracking Harry ("enough adulteries in my casebooks that Reno ought to give me a key to the city . . .") would be hard to take if it were not for Bridget. One can suffer Harry as he provides a foil for the ex-nun, who lectures her employe: "There are facts, Harry, and there are truths." And at another time she cites St. Thomas Aquinas, who ruled that a merchant who refused to pay a prostitute still owed "the lady in question her fair pay for a fairly contracted job" even though the act may have been wrong.

What the Doctor Ordered

IN Bitter Medicine (Morrow, $17.95), V.I. (Victoria or Vic) Warshawski, the gutsy female private eye with a tough mind and a tender heart, suspects malpractice when a pregnant teenage friend loses her baby in premature birth and then dies after being treated in the emergency room of a private hospital.

Soon Warshawski finds herself embroiled with street gangs and fanatical anti-abortion demonstrators, who lay siege to the clinic operated in a low-income neighborhood by her friend, Dr. Lotty Herschel. If she is attracted to the young doctor who heads the hospital's obstetrical division, Warshawski also is suspicious of the smooth-talking hospital director. Then Lotty's young black assistant, who rushed to attend the dying teenager, is found murdered. So is the less-than-bereaved father, who hangs around with a street gang.

Author Sara Paretsky does not write a tidy story. Her Chicago is gritty and zesty, enlivened with an ethnic mix of Hispanics, blacks, Poles, Italians and Lithuanians and her strength lies in memorable scenes and people. There is old Mr. Contreras, who tends his tomato plants and tries to protect Warshawski. Mrs. Alvarado, mother of the dying teenager, waits impassively in the hospital waiting room and "didn't want to talk, didn't want to do anything but sit with her sorrow wrapped around her, a sweater on top of her cafeteria uniform."

Bitter Medicine is the fourth entry in this topnotch series with one of the best female private eyes in the business.

D.C. Detective

THE BEST thing about Deadly Resurrection (Walker, $16.95) is the Washington scenes, from Embassy Row diplomatic receptions to 14th-Street massage parlors. And the dialogue could be overheard on the Metro: "I'll believe that on the day the Senators come back to RFK stadium."

But James T. Doyle's first mystery is largely derivative, recycling hard-boiled characters, tough talk and rough action. Private-eye Dan Cronyn would be a likable narrator-hero if he didn't indulge in so much moody introspection about his past in the '60s radical movement. If Doyle can pare down his overstuffed plotting there could be a modestly rewarding future for Cronyn.

Jean M. White reviews mysteries for Book World on the third Sunday of each month.