A novel set in 17th-century Oxford, with its Puritan scholars and Renaissance men, stirred considerable interest, both in sales and with the critics, when it was published last year. Iain Pears's Instance of the Fingerpost, just released in paperback, is described as a historical mystery-with words like "tour de force" thrown in. What Umberto Eco did for the Middle Ages in his learned detective story The Name of the Rose, Mr. Pears is apparently trying to do for late-Renaissance England. Thus, the mystery plot is almost obscured under nearly 700 pages of discourse on 17th-century medicine, politics, intrigue, science, and academia-all true to the times, but for one glaring exception. Like the Oscar-nominated movie Elizabeth, its historical sympathy and accuracy stops dead when it comes to religion. A complex plot winds around a murder: Dr. Grove, a fellow of New College in Oxford, is evidently poisoned one night in his rooms. Suspicion gathers around a serving girl, who is arrested for the crime and eventually hanged. Four separate participants give their version of events-all claim to know who really dunnit, and only one is correct. Or is he? By the middle of the book a reader should begin to recognize that Mr. Pears is playing with the notion of truth itself. What's real and what is merely perception? This theme has become a cliché of postmodernist fiction, reflecting today's fashionable notion that we can never know objective truth. Mr. Pears is attempting postmodernism among the Puritans. The four narrators, all very different personalities, sound suspiciously alike in vocabulary and style, and for an acknowledged "literary" work the writing falls rather flat. It does the job, but never crackles or sings. The plot is meticulous but labored, lumbering like a top-heavy coach through the story and stopping at every single village and hamlet along the way. The manuscript could have been cut by a third. But the book's most blatant fault concerns its central character, the enigmatic Sarah Blundy: despised and rejected of men, wrongfully accused and unjustly executed. Sound familiar? Christ-figures are not unknown in literature, but this one pushes the limits when her lover Anthony Wood confesses to her: "'You are my savior, the living God.'" After dropping this bombshell Anthony continues, "[I]n that sentence, I stepped forever out of the full society of my fellow men and into a peace of my own." Of course, he is merely stepping into the congenial society of 20th-century postmodernism. Mr. Pears is not playing fair. The 17th century had its share of religious cranks and heretics, and he is free to sympathize with them. But in a novel of the Puritan age, accurate in most details, a clear exposition of Christian orthodoxy is conspicuously lacking. Anthony Wood should at least get a grilling from John Owen for his blasphemous confession: "What do you mean by 'savior,' sir? Saved from what?" None of the avowedly Christian characters appear to believe biblical doctrine; they shape their own faith, not the other way around. After plowing all the way through An Instance of the Fingerpost, modern readers may now think they understand something about classic religious controversy. More than likely, though, they will only be confirmed in their contemporary prejudices.