BOOK REVIEW : An Eccentric Look at a Changed America : THE KING OF BABYLON SHALL NOT COME AGAINST YOU by George Garrett; Harcourt Brace $24, 336 pages

In the first week of April 1968, in what readers of George Garrett’s new novel will only provisionally call the real world, Martin Luther King Jr. was assassinated in Memphis, Tenn.

In the novel’s overlapping fictional worlds, a midget evangelist and a local girl, a religious mystic, are slain in the sleepy central Florida town of Paradise Springs. The evangelist’s 300-pound common-law wife and his manager are convicted of murder.

A revival tent is set afire after snakes used by the evangelist are inexplicably released into the crowd. The town’s only Mercedes is stolen and wrecked. Photographs of nudes fall from the sky. An itinerant pilot is assaulted--his genitals painted red, white and blue--in a practical joke intended for someone else.

A minister is found dead in his home. His wild and beautiful daughter runs off with a serial killer. Their first victim is a teenage gas station attendant in a neighboring town. Her ex-boyfriend, Billy Tone, before being left behind, hears the shot.

All in that same week.

A quarter-century later, Tone returns to Paradise Springs to write a nonfiction book about the “season of local madness” that coincided with race riots, the Vietnam War and the unleashing of social and cultural forces that have changed the nation almost beyond recognition.

Aided by an astute young librarian, Eleanor Lealand, with whom he begins an affair, Tone digs through files, ransacks his own memory and interviews people who were there in ’68.

Garrett has written 25 books--fiction, poetry, plays and nonfiction He’s a pro, and the unusual structure of “The King of Babylon Shall Not Come Against You” is carefully considered.

Tone’s job is to assemble the information he unearths into some kind of meaningful whole. Garrett gives us more fragments than Tone has--the taped interviews, court transcripts, essays on artifacts of the Old South, scenes of 1968 from various characters’ viewpoints, depositions from unlikely witnesses, even messages from the Great Beyond. Then he shrugs and wishes us luck.

Tone talks to Moses Katz, professor turned pornographer; Darlene Blaze, sexpot turned spiritualist; Penrose Weatherby, a Machiavellian little boy turned developer; his father, Jack, a legless Korean War vet turned unregenerate racist; Jojo Royle, a World War II ace turned disc jockey; W.E. Gary, a prominent black attorney descended from bootleggers; a white man called “The Poet” who is writing a book about how King’s death turned a flawed human being into a saint; newspaper editors and law enforcement officers past and present. Plus others.

They all have opinions. Quoting them is Garrett’s shorthand way of providing context for his story--a combination mystery, sex comedy and meditation on good and evil that recalls the work of Walker Percy.

Politically and philosophically, these opinions run the gamut, yet few of them are stupid or ill-considered, even the racist’s. The result is a novel that continually surprises and unsettles us.

Garrett, slipping his characters’ skins on and off so deftly, doesn’t state his own views, but they are clear. Too sophisticated to adhere to any of conservatism’s contemporary dogmas, he is nonetheless a conservative by temperament.

He has written--as suggested by his title, a quotation from the prophet Jeremiah, mocking the ancient Israelites’ belief that they were immune to calamity--a lament for what has happened to the United States. He mourns the sweeping away of regional differences by mass culture and the wholesale substitution of media images for reality.

Garrett feels, on balance, that Americans should fight in their wars, even the dubious ones; that it is preferable to have strong convictions even if they are wrong, and that foolish and corrupt religion is better than none.