Broadcast: Saturday 21st September 2013
11:00am-12:00pm CDT (16:00 GMT) < > « »
BBC Entertainment (Latin America)

Featuring: Matt Smith, Arthur Darvill, Karen Gillan, Elizabeth Berrington, Suranne Jones, Adrian Schiller, Michael Sheen

The Doctor follows a Time Lord distress signal to a mysterious asteroid in a Bubble Universe - could there really be another living Time Lord out there? But the asteroid hides a secret which could threaten the existence not only of the TARDIS crew, but...