Martha and the Doctor explore a large, drifting starship, the Castor, and begin to learn what overcame the crew and continues to power the vessel, in which they discover a countryside that contains a foggy village and wandering children.

Dr. Who arrives on Tiermann's World to persuade Professor Tiermann and his family that they need to get away before the arrival of the Voracious Craw, a hungry alien creature, but their efforts to leave are hindered by their full-automated Dreamhome, which has its own opinions about who should stay and who should go.

The Doctor and Martha land in the Lake District in 1909, where a giant, scaly monster terrorizes the Lakes, and King Edward VII promises a knighthood to whoever finds the Beast as a battle of wits wages on, with the fate of the world hanging in the balance.

Doctor Who and Rose arrive on the Paradise Planet of Laylora to find its perfect eco-system failing as creatures from ancient legends stalk the land, and the Doctor suspects the events are linked to a group of human explorers who have crash-landed on the planet.

Aboard the Wheel, a ring of ice and steel turning around a moon of Saturn and home to a mining colony supplying a resource-hungry Earth, the Doctor, Jamie and Zoe become enmeshed in a critical situation. Suspected of sabatoge, they soon find themselves caught in a mystery that goes right back to the creation of the solar system. A mystery that could kill them all.