The Doctor and UNIT investigate Ruby's past. But as the Time Window reveals horrifying secrets from Christmas Eve, the mysterious Triad Technology unleash the greatest evil of all.
Discover 11,128,835 listings and 280,381 playable programmes from the BBC
The Doctor and UNIT investigate Ruby's past. But as the Time Window reveals horrifying secrets from Christmas Eve, the mysterious Triad Technology unleash the greatest evil of all.
BBC One
