The BBC have revealed the synopsis for "The Magician's Apprentice" - the first episode of Series 9 which will air in the UK on Saturday 19 September 2015:
Where is the Doctor? When the skies of Earth are frozen by a mysterious alien force, Clara needs her friend. But where is the Doctor, and what is he hiding from?
As past deeds come back to haunt him, old enemies will come face-to-face, and for the Doctor and Clara survival seems impossible.
Writer: Steven Moffat
Director: Hettie Macdonald
Producer: Peter Bennett
Cast: Peter Capaldi and Jenna Coleman
Guest cast: Michelle Gomez, Jemma Redgrave, Kelly Hunter, Clare Higgins, Jaye Griffiths, Harki Bhambra, Daniel Hoffmann-Gill, Joey Price, Aaron Neil, India Ria Amarteifio, Dasharn Anderson, Demi Papaminas, Jami Reid-Quarrell, Benjamin Cawley, Stefan Adegbola, Shin-Fei Chen, Lucy Newman-Williams, Barnaby Edwards, Nicholas Pegg, Jonathon Ojinnaka.