The Doctor discovers a starship trapped in a time warp over the planet. Meanwhile, public schoolboy and secret alien Turlough crashes his math teacher's vintage car. The Black Guardian makes him an offer.

Two alien seed pods are found buried in the Antarctic permafrost and the Doctor realises that they are from a Krynoid, a form of plant life that infects and transforms all animal life on planets upon which it becomes established.

Two alien seed pods are found buried in the Antarctic permafrost and the Doctor realises that they are from a Krynoid, a form of plant life that infects and transforms all animal life on planets upon which it becomes established.

The time travelers are miniaturized.

The tiny time travelers take action.

The Kinda is apparently a primitive tribe but three team members have already vanished.

London residents turn out for the 1814 Frost Fair, but revelers are disappearing through the frozen Thames.

The Doctor makes a final stand against an army of Cybermen in order to protect humans from destruction.

The White Guardian recruits the Doctor. The Doctor is sent on a quest to collect the six segments of the Key of Time that are scattered throughout the universe.

While in Victorian-era London investigating oddities such as spontaneous combustions and a dinosaur in the Thames, Clara struggles to know the man the Doctor has become.

In order to find the second segment, the Doctor must defeat the Captain of Zanak, a hollow ship which absorbs the natural energy of planets.

The Doctor and Romana arrive on scene where they meet Professor Amelia Rumford and her assistant Vivien Fay, who are working around the stone circle. When the Doctor discovers a spaceship hovering over the circle, his life is jeopardized.