By rumor and official dispatch, news had come to Shrewsbury of a terrible betrayal. Philip FitzRobert, one of the Empress Maud's greatest champions, had turned coat, imprisoning thirty knights and squires who held true to the empress. The lucky ones had kin who could afford the dear price for their freedom; the others had to rot in captivity. Among the missing and unclaimed was Olivier de Bretagne, an exceptional knight whose mother had been a woman of the East - and whose sire, unknown to Olivier himself, was Brother Cadfael. It had happened during the Crusades, years before Cadfael had become a monk. Indeed, Cadfael did not know he had a son until by chance he met Olivier as a young man. But the bond is strong, and it is the one claim that can make Cadfael break his vows and drive him from his cloister, risking the religious way of life he so loves. A father first and a brother second, the monk travels to Coventry, where a great conference holds faint hope of a settled peace and clues to his son's whereabouts. Instead, he finds Olivier's hotheaded young brother-in-law Yves, who is also searching for the missing knight. And he comes, too, upon the brutal murder of a renegade lord who had thrown his support to Philip FitzRobert. Soon Cadfael has a double quest...to save Yves from deadly danger and to find the dungeon where his secret son, and final penance, are waiting.