<p>*Warning: This episode contains spoilers for *Dark Angel.</p>

<p>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.</p>

Writer Daisy Coulam Finds Humor in Grantchester's New Season

MASTERPIECE Studio is your backstage pass to the PBS series—from Sherlock to Poldark. After the show, turn off the TV and tune in to MASTERPIECE Studio for the scoop with host Jace Lacob. Listen for exclusive interviews with the cast and crew of your favorite shows. Get the history lowdown behind the people and places you see on screen, and hear revealing stories from the set. MASTERPIECE Studio is made possible by Viking Cruises and Raymond James. Sponsors for MASTERPIECE on PBS are Viking Cruises, Raymond James, and The MASTERPIECE Trust.