As Donna and the Doctor stand in the middle of a bleak and empty plain, on some remote planet no one on earth has ever heard of, the tops of the distant mountains, way off on the horizon, suddenly seem to catch fire.
The planet’s sun is slowly rising, its light catching the crystals that millennia of weathering by wind and rain have exposed on the mountain peaks. They sparkle in every conceivable colour, their radiance so dazzling that Donna’s grateful for the protective goggles she’s wearing.
“Pretty isn’t it?” the Doctor says, grinning at her.
“Pretty? It’s bloody incredible!”