The Tenth Doctor and Heather McCrimmon land on a small planet that looks like a pearl in the middle of a distant galaxy. They discover the planet is composed of a silk-like substance. Two figures rise out of the ground and, still attached to the planet, give chase. The figures bear a strong resemblance to the Doctor and Heather. They fall through a hole in the ground. It leads to an underground chamber. The low gravity of the planet breaks their fall. They explore the chamber with its pools of luminous green slime and find a long dead giant spider.