In one of the most surprising moments of the series eight opener, the Doctor trapped Clara inside the lair of the clockwork robots, thus demonstrating what we have now come to realise is his ruthless nature. While it was later revealed that the Doctor never left, we were presented with an incredibly tense moment where Clara was forced to mimic the organ-harvesting robots around her in a desperate attempt to make an escape. Up to this point it wasn't clear what the episode title meant; but here we saw Moffat at his very best, taking a simple human action and crafting a terrifying sequence around it. Clara wanders through the clockwork robot's lair, tears running down her face as she furiously attempts to survive. The audience was holding its breath with her, right up to the point where she seems to escape, only to stumble into a tunnel filled with many more robots. Clara fails and we wondered just what her fate would be. It was an incredibly tense moment that stood out as the highlight of this dark and forbidding introduction to the new Doctor.