The BBC released a preview for the Series 8 finale for Doctor Who, episode 12, "Death in Heaven."
Doctor Who airs Saturdays on BBCA starring Peter Capaldi and Jenna Coleman.
With Cybermen on the streets of London, old friends unite against old enemies, and the Doctor takes to the air in a startling new role. Can the mighty UNIT contain Missy? As the Doctor faces his greatest challenge, sacrifices must be made before the day is won.