S7, E4: The Power of Three
The Doctor and the Ponds puzzle an unlikely invasion of Earth, as millions of sinister black cubes arrive overnight, almost like presents falling from the sky. But what are they, what’s inside them and most importantly, who sent them? With the international community at a loss, it’s left to the Doctor to unearth who is behind the mystery.
Starring Peter Cartwright, Mark Williams, Jemma Redgrave