Dead Man's Ransom — Ellis Peters

The civil war between King Stephen and Empress Maud is raging, and in the fierce Battle of Lincoln, Gilbert Prestcote, sheriff of Shropshire, is taken prisoner. But his captors have also lost a man of value -- headstrong young Elis ap Cynan is delivered to the good monks of Shrewsbury after he's found almost drowned in a nearby stream.

A trade of the two prisoners is arranged, but while Elis is being held in Shrewsbury he falls in love with Prestcote's daughter, Melicent. What future can they hope for when he must return to Wales in exchange for her father's freedom?

Then Prestcote is murdered and young Elis is the object of every suspicion. Only kind Brother Cadfael, herbalist monk and cunning amateur detective, can untangle the threads of this delightful mystery. Indeed, a thread of wool -- bright, clear blue wool -- holds many answers…