August, 1476: Roger the traveling chapman - whose sharp wit and tender heart have been involved in affairs toucing the mightiest and humblest in the land - ought to be on his way home to Bristol after a peaceful summer's peddling. But a request from the Duke of Clarence to escort a young bride traveling to meet her betrothed takes him instead to Glastonbury - and an extraordinary adventure.

The bridegroom has vanished, and Roger - with his insatiable curiosity and gift for solving puzzles - delays his journey home to help find the missing Peter Gildersleeve. Not two days have passed before Peter's brother, Mark, also disappears under mysterious circumstances. The town is full of gossip, and rumors of the devil and black magic abound.

Roger links the disappearances to the discovery of an ancient manuscript written in a strange language. As Roger gradually deciphers the manuscript's meaning, he concludes that a greater mystery sill may lie at the heart of the brothers' disappearance...