Strange things are afoot in the year 1327. A Bavarian has assumed kingship over an aggregation of city-states scattered across northern Italy, earning the ire of the pope, who excommunicates him. The pope also condemns the foundational tenets of the poor and peaceful Franciscan order, leading the Bavarian king to think that he might do worse than ally himself with the guys in the rough cloth robes. There’s nothing like a little political intrigue to set a schism rolling.

Stranger things still are afoot in a well-built if gloomy monastery in the mountains of northern Italy. Some of the brethren are going missing, then turning up dead, one sopping in a cask of pig’s blood, another crushed beneath a rockfall, a third drowned in his bath. Suicide, poison, homicide: There are dark mutterings that the devil stalks the land, and maybe even a witch or two.

Into this blood-soaked scene comes William of Baskerville, a Franciscan brother, and a Benedictine novice named Adso of Melk, the narrator of a tale of scholarly investigation that in time links the murders to—well, to books, for the abbey, says William, “has more books than any other Christian library.” That’s not necessarily a good thing, William tells Adso, for too much reading can lead a person to think strange thoughts.

Umberto Eco, the bibliophile’s bibliophile, takes the occasion of his novel The Name of the Rose to imagine a place of his fondest dreams, a library hidden away in secret passages, full of odd and occult knowledge. The foundational conceit of the narrative is that Adso is telling the tale of William’s diligent sleuthing, a tale that we have today because the manuscript was handed off centuries later to that quiet, bespectacled Italian professor to edit and publish.

It makes for an epic private joke, for Eco was known in 1980 mostly to students of semiotics, the formal study of signs and symbols. Eco, with a long interest in all things medieval, had been toying for some years with the thought of introducing a Sherlock Holmes–like character into the world of theological disputations and autos-da-fé, and he found a perfect fit in William, an imaginary character who shares some points in common not only with Holmes, but also with William of Ockham, William of Baskerville’s supposed teacher and the inventor of the logical “razor” test that bears his name. Yet William’s every success of inference is met by some awful happening—including the worst thing a bibliophile can imagine, the burning of a library full of rare books.

Published in 1980 in Italy as Il nome della rosa, Eco’s novel was a surprise bestseller there. It sold just as well in other languages, including the English of William Weaver, whose rendering, The Name of the Rose, was published in 1983. Indeed, the book is said to have sold more than 50 million copies worldwide, making Eco, who died in 2016, very wealthy indeed. And what did he do with the proceeds? Naturally, he bought more books.

Gregory McNamee is a contributing editor.