Watch: Doctor Who "Heaven Sent" Featurette
Check out an introduction for the next episode of Doctor Who, "Heaven Sent," from showrunner Steven Moffat and Peter Capaldi.
If you haven't seen the last episode, you may want to skip this as it connects to a spoiler.
Doctor Who airs Saturdays on BBCA.
Trapped in a world unlike any other he has seen, the Doctor faces the greatest challenge of his many lives. One final test. And he must face it alone. Pursued by the fearsome creature known only as the Veil, he must attempt the impossible.