Jakes is back to the fall of Dixie in Prologue talk By Marilyn Bowden
   Historian and novelist John Jakes, whose popular trilogy North and South topped bestseller lists around the country a decade ago, has returned to a Civil War setting in his latest book, On Secret Service.
   Mr. Jakes will be the speaker at a noon meeting of the Prologue Society Oct. 30 in Northern Trust Bank, 700 Brickell Ave. The society, co-sponsored by Northern Trust and Miami Today, is dedicated to the appreciation of works of history. Details: (305) 789-1344.
   "The history of spying in the American Civil War is a subject that intrigued me the moment I discovered it years ago," he writes in an afterword to the novel. "I promised myself that someday, when I had an opportunity and a publisher who shared my excitement, I'd write a novel about it."
   The book's twin plots follow the wartime adventures of two pairs of lovers. A northern spy is attracted to a southern belle whose family is embroiled in particularly unsavory political activity. An idealistic young actress who is captured while masquerading as a Union soldier falls in love with a disillusioned Confederate major.
   The portrayal of historical personalities is one of the difficulties of this genre. Too often novelists faced with introducing well-known figures such as Abraham Lincoln or Gen. George McClellan are bowed down by the weight of myth and history. The result is stiff, unconvincing caricature.
   Happily, Mr. Jakes doesn't suffer from this fault. His characters, invented or resurrected, are equally convincing.
   "Lincoln hit his silk hat on the door, grabbed it before it tumbled off," he writes. "He laughed, and his eyes fixed on Lon. `Say, I've seen you before. First time was in Harrisburg, wasn't it?'"
   Perhaps the best of his historical portraits is the rather enigmatic Allan Pinkerton. A Scot by birth, he set up the first US detective agency in 1850. Under McClellan, the agency organized Secret Service activities for the Union during the Civil War.
   Lon Price, a young agent who is among the novel's main characters, begins by idolizing Pinkerton. By the book's end, he's become thoroughly disillusioned.
   His disenchantment is only partly a by-product of living through a particularly bloody, internecine struggle that dragged on far longer than anyone expected, as wars are wont to do. It's also represented as a result of the agency's poor showing during the war years — an ineptitude generally attributed to Pinkerton's crippling dependence on Gen. McClellan.
   Civil War buffs will find On Secret Service a rich field for controversy. Mr. Jakes serves up some interesting takes on lingering questions.
   For example, was John Wilkes Booth, Lincoln's assassin, the pawn of a conspiracy plot hatched in Richmond? And was a faction of his own party, frustrated by what they saw as a as a compromised Reconstruction plan, collaborate?
On Secret Service, by John Jakes, 448 pages hard cover, is $25.95 from Dutton, a member of Penguin Putnam.