Brother Cadfael is the fictional medieval monk of Shrewsbury, England, who is both herbalist and detective in Ellis Peters' Brother Cadfael mysteries. Although a 12th-century monastery seems an unlikely place to need a detective, Brother Cadfael is often called upon to solve a mystery (murder, more often than not) in the Shrewsbury area. Unlike modern detectives, he cannot rely on modern forensic methods to solve the crime; instead, he relies on his knowledge of human nature, the natural world, and his faith in God to root out the evildoer.
Brother Cadfael was born Cadfael ap Meilyr ap Dafydd, in Trefriw, in May, 1080. As a young man he fell in love with Richildis Gurney, but left her to go on a crusade to the Holy Land, vowing to return and marry her. However, he was gone for years, and by the time he returned, she had married another. Cadfael returned to the Holy Land as a crusader, visiting Venice and Cyprus, and fighting at Antioch and Jerusalem, among other places. In Antioch he met Miriam, a Syrian woman with whom he had a relationship before he moved on to Jerusalem.
Returning to England, he found -- to his relief -- that Richildis had married. He fought for the English in Normandy before deciding to leave the soldier's life and become a monk, entering as a novice in Shrewsbury Abbey. Using plants collected on his travels about the Mediterranean and the Holy Land, he made the gardens of Shrewsbury Abbey among the finest in all of England. Although he in his modesty would never claim so, Brother Cadfael is also one of the finest herbalists in the country.
It is at this point that the Chronicles encounter him: A former soldier who has happily become a holy brother, devoting the remainder of his life to God. However, despite being cloistered, his adventurous spirit remains strong. That independent spirit, along with his keen mind, helps him to serve God by rooting out evil and solving crimes. Although some others in the abbey take a dim view of Cadfael's apparent worldliness, Cadfael himself knows that, despite his fallible nature, he is doing his best to serve God with his actions, rather than putting on an empty show of piety.