April, you may recall, is when folks long to go on pilgrimages. If you slipped into a funny accent when you read that sentence, or - worse - it launched you on a recitation of many more strange lines, then you've studied "The Canterbury Tales."
Making us memorize Chaucer's Prologue was a favorite torture among my teachers. In graduate school, Dr. Carter Revard stood over me as I plodded through the medieval verse, interrupting on every word, sometimes every syllable, to correct my chronic mispronunciation. April was the cruelest month.
Natheless, even if Middle English left you in a muddle or you never studied it at all, you'll be fascinated by Peter Ackroyd's gripping new mystery, "The Clerkenwell Tales." Known primarily for his masterly, 800-page study of London, Ackroyd has now written a book that's nominally fiction and strikingly brief. (Look for his equally efficient biography of Chaucer in January.)
The story opens in 1399 at the House of Mary, a convent in Clerkenwell, London. After a brief illness, a young nun named Clarice has begun describing strange and violent visions. The prioress suspects it's all a stunt - just what she might expect from this scandalous girl who was conceived in the tunnels beneath the convent.
But the country is agitated and unsettled over the power struggle between King Richard II and Henry Bolingbroke (Henry IV). Rumors of rebellion roil the populace. City leaders fret about unrest and wonder which side to support. An intractable nun making prophecies of plague and regicide could be the match that ignites a conflagration.
Touches of Middle English dialect flavor this narrative but never obscure it. With a nod to Chaucer, Ackroyd moves through 22 short tales, each named for a different character, some familiar from that legendary pilgrimage. (The Wife of Bath steals the show, again.) In this case, though, all the tales contribute to the same developing story about a crisis in London, and they're told about - not by - their title characters. The mystery builds up like a mosaic whose secret pattern the artist knows but won't tell till we can finally see it ourselves in the last pages.
When Sister Clarice cries out that "all the churches of England will be wrecked and wiped clean," she's merely adding her radical voice to an ongoing theological and political debate. But when she correctly predicts a series of terrorist acts in the city, she unsettles both her skeptics and her supporters. The problem (and pleasure, for us) is how to distinguish those two groups and figure out what plots these convoluted alliances are pursuing.
The nun's prescient ravings play right into the rebellious plans of Bolingbroke's friends in London who want to show how poorly King Richard protects the Church.
But a maniacal friar named William Exmewe seems just as interested in using Clarice for his own ends. He's secretly leading a group of radical purists known variously as "the true men," "the foreknown," or "the predestined ones."
In the interest of purifying the Church, they begin a campaign of terror in London. Rejecting all ecclesiastical ceremonies and officers, these cultists believe that as Christ's true followers they're absolved of all sin. Their actions - murder, arson, package bombs - are prompted wholly by the spirit of God. "If anyone hinders us then God's curse is upon them," Exmewe instructs. "To kill is to be free." Victims of their terrorist acts simply return to "the source." And their own deaths are nothing to fear because salvation is assured.
The comparison to contemporary Islamic terrorism is, of course, impossible to resist. And Ackroyd does a chillingly effective job of demonstrating how cynical men twist the faith of simple fanatics to their own murderous ends. Only the symbols have changed. In this alarmingly familiar theological madhouse, anything is permissible, no opposition is valid.
One man, a physician, has the wherewithal to begin piecing contradictory evidence together to solve this crisis, but the forces involved are far larger and more evil than he supposes.
Part of Ackroyd's genius here is his ability to capture London at a time when it looks and sounds surreal to us - a fascinating mixture of the familiar and the alien. Englishmen of 1399, after all, acted and talked almost like we do. They lived in towns, worked at trades and professions, shopped in markets, and even enjoyed a degree of leisure.
And yet their streets were a ghastly mess of sewage, animals, and the dispossessed. Most people couldn't read, but they understood the power of written words. Their legal system was a hodgepodge of rights and cruelties. They knew something about biology, physics, and chemistry, and yet still considered the world infused with supernatural forces. Indeed, Ackroyd's emphasis on their wacky nutritional and medical theories - and the confidence they placed in them - should give us pause. Will today's statins be yesterday's boar grease? "There's never a new fashion, but it's old," as Chaucer said.
Of special interest to these medieval characters is the tension between predestination and free will. New ideas about God and man, combined with the Church's crumbling doctrinal control, were leading more and more people to ask troubling, radical questions. If God knows everything that will happen, what role is left for us to make our own decisions? Are we responsible for anything in a world where God controls everything? For Friar Exmewe and his band of terrorists, God's omniscience offers absolution for whatever they might do, but others are more profoundly shaken by this quandary.
In Ackroyd's dramatization, all these arcane theological and political issues come bracingly alive as the plot turns and twists through a murky world of betrayal and fanaticism. In the words of "The Monk's Tale" - with apologies for my pronunciation - "To thee this storie I recomende."
• Ron Charles is the Monitor's book editor. Send e-mail comments about the book section to Ron Charles.