A familiar noise broke the silence and the Doctor whirled around in time to see the TARDIS dematerialise from behind him.
"Can't say I blame you," the Doctor muttered into thin air, "I wouldn't stay out here if I had the choice."
He stood for a few moments contemplating the swirling mist, but did not spend too long thinking about the disappearance of the TARDIS. She would return once they had finished what they had come to do. Whatever that was.
Snapping back into reality, the Doctor grinned and spoke aloud, "Hang on, I have got a choice! I'm hardly going to find anything around here."
He began to stride purposefully towards the hill, before tripping over smaller coral blooms hidden beneath the mist. It made sense to head for the only significant feature in the landscape. Deciding that a slower pace was more appropriate, he picked his way through the mist, stopping briefly to examine the coral, but moving faster as the temperature dropped and the mist thickened. The slow, steady pulse beat beneath his feet for several minutes, until the Doctor found himself in a slight valley between a gentle slope and the steeper rise of the hill before him. He instantly missed the sensation. There was something oddly comforting about the steady heartbeat as it became colder and more difficult to see.
As he approached the side of the hill, the Doctor got the feeling that this was where he could begin to understand what was happening on this moon. Even if there was nothing obvious, he could at least find a better view of his surroundings. The Doctor leaned over and touched the base of the hill, tracing his fingers up the gravelly surface as he gradually walked around the base. The hill was steeper than the Doctor had imagined. As his fingers moved across the surface, the Doctor noticed the evenness gradually change into a rougher, cracked texture.
"I wonder…" the Doctor mused, as thin pieces of the calcified crust came away in his hand. He stopped moving and, kneeling down, leaned over and rubbed the peeling crust away from the ground. As it became difficult to see, the Doctor took a small torch from the pocket inside his jacket and shone it on the ground. In the areas where the softer coral had been brushed aside, the ground gleamed brown and green like spilt oil. The Doctor sat up, brushing his hands against his trousers, a smile spreading across his face.
"I love it when I'm right."