The official synopsis runs:
“Orbiting a quiet backwater planet, the massed forces of the universe’s deadliest species gather, drawn to a mysterious message that echoes out to the stars. And amongst them – the Doctor. Rescuing Clara from a family Christmas dinner, the Time Lord and his best friend must learn what this enigmatic signal means for his own fate and that of the universe.”
Artwork and a trailer has been released alongside the announcement. Returning foes include the Daleks, the Cybermen, the Weeping Angels and the Silence. The Time of the Doctor will see the Eleventh Doctor return to Trenzalore, his supposed final resting place, and all indications are that the phrase “Silence will fall” (recurrent since Series 5) will finally be explained. No word yet on whether River Song (Alex Kingston) will be appearing but given her vital presence within Matt Smith’s era of Doctor Who it seems almost impossible that she should be left out.
The Time of the Doctor is expected to be transmitted on 25 December 2013 and will introduce Peter Capaldi as the Twelfth Doctor (whose eyes were briefly seen in The Day of the Doctor).