Brother Cadfael, the medieval mystery-solving monk, is a fascinating detective, at once a man of God, of science, and even of action. Derek Jacobi stars as the former "soldier, sailor, sinner, and Crusader" who has his faith tested by crimes of royal intrigue and baffling murders that seem to plague 12th-century Shrewsbury. You'll find few Benedictine monks so skilled at using a quarterstaff, but beware never to tell him your theory of how a crime "must" have been committed. "We must always be wary of 'must'," he states. "Nothing is certain." And so attest these divine mysteries based on the books by Ellis Peters. Each feature-length episode is self-contained but plays against the backdrop of England's civil war between forces loyal to King Stephen and those to Empress Maud. Eoin McCarthy costars as local Under-Sheriff Hugh Beringar, who relies on Cadfael when murder subverts his efforts to keep the peace. --Donald Liebenson