Ellis Peters: The Leper of Saint Giles
Brother Cadfael series
A marriage is about to take place at the abbey; the groom is a strong, thick-set man over 50, very rich; the bride is a young 18 year-old, orphaned, taken care of by a wicked uncle and aunt – the uncle is her dead mother’s brother; she is enormously wealthy, but the uncle and bridegroom between them will divide all her lands. She doesn’t want to marry him, and is in love with a young squire to the bridegroom. The bridegroom is murdered on the eve of his wedding; the young squire has already been thrown out of his master’s house and accused of theft, but he escaped from the sheriff’s men and is in hiding with the lepers of St Giles. Brother Cadfael sets out to find the murderer; the young squire is accused, but Cadfael and the girl believe him innocent, as does his friend, Simon, the nephew to the murdered man. Cadfael traces the man’s mistress, and from her discovers the name of the only person who knew where she was, and hence where the bridegroom was on the eve of his wedding.

There's a happy ending, of course!

I had read this before but had forgotten almost every detail, even the actual perpetrator. It’s a classic Brother Cadfael mystery, the identity of the perpetrator well hid in clear view; well-researched use of words as they would have been used in the 12th century – ‘capuchon’ ‘jennet’ ‘assart’ and so on; the history of the civil war between King Stephen and Empress Maude; the Crusades; the daily life of the Abbey and the monks; the situation of lepers in those days; all these details add interest to the basic “whodunit”, with a riveting plot that had me holding onto the book until late at night even the second time around. This book has also been produced as a TV episode in the Brother Cadfael series, so if the story sounds familiar, that may be why.