The term "instance of the fingerpost" was coined by Sir Francis Bacon, one of the great English champions of the scientific method and inductive reasoning. Though the clunky phrase might not seem to construe much of a debt, the ideas behind it are in large part the basis of every whodunit written since. In mysteries, the instance of the fingerpost is the sudden revelation that makes the detective finally whisper, "But of course!"; it's the thing that makes all the other pieces of evidence make sense. A good such instance can make the difference between a mystery's brilliant solution and a mere letdown in which everything magical about the first part of a mystery is mundanely explained away. Iain Pears' latest book focuses deliberately on the ingenious and satisfying, which is how a mystery novel that baldly pays tribute to its ponderous Baconian debt can be so readable and fun. Pears plops a corpse in the middle of Oxford in 1663, when Bacon's philosophies of investigation were still being dramatically put to the test. (Many of his famous disciples and detractors are mixed up in the mystery in significantly more than cameo roles.) The story is told in a smartly executed variation on the four-narrator Rashomon style: We first hear about the dead man, a curmudgeonly fellow of New College named Robert Grove—who, incidentally, is also real—in an Italian travel narrative by Marco da Cola, a gentleman who happened to be in England at just the right time to meet the victim and observe critical events in the course of the investigation. Three characters within da Cola's narrative subsequently take issue with various details in narratives of their own that present the murder and its investigation starting from different premises and in different contexts. Each narrator tells a book-length story complete with an investigation and a convincing theory as to the identity of the killer and his or her motive. Not surprisingly, none of the narrators are entirely reliable, and each version of the story contains its own mixture of truth, omission, self-deception, and misdirection. What's more, Pears denies his characters the anachronistic 20th-century knowledge and wisdom often granted to historical detectives. Consequently, each narrative is further distorted by contemporaneous attitudes, knowledge, and prejudice, and not even "the truth" is always what it seems. The results are fascinating, the eventual payoff is well worth Fingerpost's 600+ pages, and the brilliantly realized narrative voices and stories are emotionally engaging enough to transcend the dry logical game it could have become.