The BBC have released the synopsis for the penultimate episode in Series 9 - "Heaven Sent" - which will air on BBC 1 on Saturday 28 November 2015:
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. If he makes it through, Gallifrey is waiting…
Writer / Steven Moffat
Director / Rachel Talalay
Producer / Peter Bennett