"Clara, follow me." The Doctor says in a unsure voice as he puts his hand back for her to hold. "I'm not holding your hand. And what's going on?" He puts his hand down, quite obviously disappointed. Clara know s by now that he fancies her, but she wasn't sure how she feels about him. "I don't know. Just stay close behind." He replies. They walk through the opening where the shadow went, and continue walking for 15 minutes. "Doctor, this tunnel is dark, shouldn't it have crystals too?" "Yes, someones been taking them. But for what? Vortlox crystals are the most antiquated fuel source there is. It'd have to be someone desperate, someone like…" "Them?" Clara points down a shaft in the tunnel leading to what looks like a factory. The Doctor runs through it with Clara following closely behind. "Who are they?" Clara asks. "Those are Sontarans, like Strax… only bad" "Who's Strax?" Clara asks. "Oh that's right you haven't met him. The Sontarans are like potatoes, only bent on taking over the universe for the Sontaran empire" The Doctor does a mock Sontaran salute and whispers "Sontar-ha" Clara giggles at this. "Now the nice thing about these guys is that they have a chink in their armor. Normally they're nearly undefeatable but if you hit them in the probic vent, on the back of the neck it'll knock them out" The Doctor picks up a rock. "Watch this" he smiles. He creeps down the passage until he is about ten feet from the sentry. He then throws the rock at the back of his neck and knocks him out. "That should give us a bit more time to look around." They walk through a door near ahead of where the sentry was standing guard. There is nothing behind this door, but another door. They open the next door and see that it leads to a catwalk overlooking a bank of computers and other machines. "Halt in the name of the Sontaran empire." The Doctor and Clara freeze. The Doctor turns and sees a familiar face wink at him from the bottom floor as he is dragged away by the Sontaran. The Doctor and Clara sigh simultaneously in relief at knowing that they were not seen.