In Doctor Who, it seems an episode isn't complete without a spooky prophecy linking in to future episodes. Saturday's Planet of the Dead was no exception either, with Carmen telling the Doctor three chilling warnings:
"Your song is ending, sir."
"It is returning through the darkness."
"He will knock four times."
So what could all these mean? Firstly, we know the Doctor's song is ending because over Christmas/New Year the 10th Doctor will regenerate as David Tennant steps down from the role to introduce Matt Smith as the 11th incarnation of our favourite TimeLord.
As for the second point, there are plenty of theories. Maybe it could be the return of Davros, or perhaps Gallifrey? This is the part I'm not sure of. However, the third point I'm absolutely positive is relating to the Master. Remember his infectious 'duh duh duh duh' of the drums? Also, some have said it could be the mysterious Midnight entity which was never revealed as it tapped on the doors of the spaceship the Doctor was travelling on... Others believe it could be Wilf knocking on the TARDIS doors...
What do you think? Feel free to post your thoughts.