It's the summer of 1144, and Brother Cadfael, herbalist-sleuth of Shrewsbury's Benedictine Abbey, has joined wise young Brother Mark on a diplomatic mission to newly installed Bishop Gilbert of St. Aspath's Church in Wales. They're soon caught up in the affairs of warring brother princes Oswain and Cadwaladr--the latter has been lying low, disgraced by his brutal actions but soon to surface with a force of Danish mercenaries to try to recover the lands taken from him in punishment by his older brother. Cadfael, Mark, and another traveler--rebellious Heledd, daughter of Canon Meirion, on her way to an arranged marriage--are captured by the Danes and held hostage. There's a murder--not solved by Cadfael this time-- and many battles of words and weapons before it's all over and Cadfael can return to the peace of his abbey. Densely packed with Welsh names and stately conversations, this isn't one of Peters's more vivacious efforts (Flight of a Witch, p. 441, etc.). English-history buffs and faithful fans will be pleased. Others may find the going a bit weighty.