A gruesomely murdered prostitute, a satanic cult, a secret book of spells, seances, psychics, opium dens, underground bars, puritans, and witches — just another raucous summer in Portland, Maine . . . though it’s not last summer, but the summer of 1892, the bicentennial of the Salem witch trials. The discovery of a murdered prostitute is the first scene in a well-paced and intriguingly contrived mystery by Portland native Kieran Shields. The victim is found with a pitchfork through her neck, a circumstance so unusual that the examining physician, Dr. Virgil Steig, suggests engaging a private detective, Percival Grey, to assist Deputy Marshal Archie Lean. Grey, whose scientific methods reveal him to be an acolyte of Mr. Sherlock Holmes, declares the murderer to be a serial killer, and the game is afoot!

Filled with arcane information, but written with a light touch, The Truth of All Things (Crown, New York, New York; 416 pages; $25) is a rollicking, entertaining, and mostly satisfying mystery set in a craftily re-imagined Portland. In 1892 Union Station is not only still standing but nearly brand new, the Fourth of July is celebrated as usual on the Eastern Prom with fireworks and excessive drinking even though the city was officially dry thanks to the Maine Liquor Law of 1855, and psychics and mediums are as thick on the ground as thugs and drunks and drug addicts, yet everyone dresses well. Shields, born in Portland, writes about the city’s nineteenth-century past with a native son’s affection and an historian’s attention to detail. Part of what makes this mystery so enjoyable is meandering with the characters down the city streets and past its landmarks, to feel the pull of the horse-drawn carriages lumbering up Munjoy Hill and the cobblestones under their wheels, to climb up the stairs into the Observatory, break into mausoleums in the Western Cemetery, and bushwhack through undergrowth around the shores of a much wilder Back Cove.

Deputy Marshal Lean accepts the help of Percival Grey, initially without much enthusiasm (“Can’t say I care much for involving some Pinkerton with half-cooked ideas about police work.”), then with suspicion since Grey is half Abenaki and a message in Abenaki was left at the murder scene. Soon enough, however, Lean begins to appreciate Grey’s abilities. Like Holmes, he is a master of disguise and deduction. (Holmes fans will delight in some overtly borrowed scenes.) It is Grey, for example, who discovers that “sticking” one with a pitchfork is a traditional way to kill a witch.

As the investigation widens, and more murdered women appear to be linked to the Portland killer, Lean and Grey seek help from Helen Prescott of the Maine Historical Society who specializes in the Salem witch trials. Once witchcraft becomes an issue in the original murder, Prescott’s historical knowledge and the accidental discovery of pages from an ancient text drive Lean and Grey to expand their investigation to a thaumaturgic society, “The Order of the Silver Lance” located on Winter Street, and to Salem itself and the Danvers Lunatic Asylum. Following leads in the late nineteenth century requires Lean and Grey to travel by buggy and train to remote places like Camp Ellis, to search out ancient books in cathedral libraries, and to rummage around in graveyards in the middle of the night. As a team, they work smashingly: Prescott knows her witchcraft, Lean doesn’t mind a bit of grave-robbing (while reciting poetry by Longfellow), and Grey performs Holmesian-type examinations of tobacco ash and plant seeds. As the plot thickens, the trio find themselves investigating not only murder but devil worship and human sacrifice, endangering their own lives in the process.

Technology, the French director Jean Renoir once said, can mean the death of art, and this seems to be true in the case of the old-fashioned detective mystery whose suspense so often depends upon the dramatic effect of delay, confusion, and lack of information — precisely those handicaps a cell phone and Internet access have eliminated from contemporary life. By setting his mystery in the same year that Arthur Conan Doyle (himself a great believer in the occult) published his first Sherlock Holmes story, Shields has written an homage to the old fashioned detective story. The ending may be a bit too long and convoluted, and the solution, when finally revealed, may be less than surprising, but The Truth of All Things has its own magic, and once under its spell, it’s impossible to put it down.