In order to escape an attack in space, the TARDIS makes an unscheduled landing and ends up deep inside the London Underground. Here the travellers soon find themselves engulfed in a terrifying battle against the Great Intelligence and the Yeti, a deadly enemy set to invade the Earth. As events progress and the menace spreads, it becomes clear that the Intelligence's goal is not just possession of Earth, but the Doctor's mind too...

This release includes all surviving episodes, plus a brand new fully animated reconstruction of the missing third episode created from the surviving audio-only recordings.

Starring Patrick Troughton, Frazer Hines, Deborah Watling, Nicholas Courtney and Jack Watling.