About this episode
*Warning: This episode contains spoilers for *Dark Angel. Fans of “Downton Abbey’s” Anna Bates were likely spooked by Joanne Froggatt’s character in “Dark Angel”: the manipulative real-life serial killer Mary Ann Cotton. In this episode, MASTERPIECE Studio dissects Mary Ann’s motives, and pulls back the curtain on Joanne Froggatt’s darkest role to date.