AN INSTANCE OF THE FINGERPOST Iain Pears (Riverhead, $27) Fans of such mystery/history hybrids as The Name of the Rose and The Alienist, pull up your chairs and settle in for a long, long wallow amid the pseudoscience, superstition, voodoo, gender relations, class structure, and politics of Restoration England. Pears' An Instance of the Fingerpost (if you think the title is a little too teasingly obscure for its own good, wait until you get a load of the novel) is a brimmingly detailed, dauntingly complex stink-and-squalor tour of 17th-century Oxford, with a murder as its chugging motor. The victim is a professor who runs afoul of a bottle of spirits dosed with arsenic; the accused killer is a poor but defiantly smart young woman who is denounced as a wench, a whore, and a witch; and the catch -- and it's a whopper -- is that Fingerpost is actually four contradictory tales, and all the accounts of the killing are offered by narrators who are variously self-deluded, self-protective, and so unreliable that from the novel's first sentence on, anything you read may be a lie.
Although that sounds like challenging fun -- and for the most part it is, if the words fun and postmodern can be spoken in the same sentence -- be warned: Pears takes more than 700 pages to play his game, and readers for whom names like Oliver Cromwell and John Locke don't crop up in everyday conversation may want to keep a British-history textbook close at hand. Bring a supply of patience as well. For each ingenious detour along this winding road, there are also dead ends and tedious dirt paths. (Come to think of it, wasn't The Name of the Rose one of the most bought, least read books of its year?) But to Pears' credit, those who drain to the last drop this bulging gourd of a whodunit will find themselves both sated and extremely surprised. B+