The episode which is written by Steve Thompson ("Sherlock") and directed by Douglas Mackinnon (Line of Duty, Doctor Who), will have Hawes playing "Ms. Delphox." She is described as "a powerful out of this world character with a dark secret. Travelling across space and time the Twelfth Doctor (Peter Capaldi) and his companion, Clara Oswald (Jenna Coleman), will come face to face with the mysterious Ms Delphox when they arrive on a strange and puzzling planet."
Keeley Hawes comments on her new role, "I am delighted to join Doctor Who and to be working with this incredible team. Ms. Delphox is a great character and someone I've had a lot of fun playing."
Lead writer, Steven Moffat adds, "Anyone watching Jed Mercurio's amazing Line of Duty will know that Keeley Hawes is having one hell of year. And now it's about to get even better as she achieves the greatest villainy yet attempted on 'Doctor Who:' she plays a banker."
The series is currently filming. We'll let you know when the next series will premiere.