The King's Thief (1955)

Edmund Purdom plays "Michael Dermott" a petty crook and the hero in this tale of a 17th Century plot by the evil, ambitious "Duke of Brampton" (David Niven) to amass a fortune by denouncing as many wealthy nobles as he can before he can depose the weak Charles II (George Sanders) and rule Britain. Ann Blyth is the daughter of one such man who was hung for treason. She enlists the help of Purdom and they set out to foil these dastardly plans with the aid of the Duke's self-incriminating little black book. It's a fine looking film, and Niven and Sanders put some class into it. Otherwise, though, the leads are quite feeble as is the script.