The TARDIS narrowly avoids becoming engulfed in a cobwebby substance in space. It arrives in the London Underground railway system, the tunnels of which are being overrun by the web and by the Great Intelligence's robot Yeti. The time travellers learn this crisis was precipitated when Professor Travers, whom they first met in the Himalayas some thirty years earlier, accidentally caused one of the Yeti to be reactivated, opening the way for the Intelligence to invade again.
as The Doctor
as Jamie McCrimmon
as Victoria Waterfield
as Colonel Lethbridge-Stewart
as Professor Travers
as Anne Travers
as Harold Chorley
as Captain Knight
as Staff Sgt. Arnold
as Corporal Blake
as Corporal Lane
as Craftsman Weams
as Driver Evans
as Soldier
as Soldier
as Yeti
as Yeti
as Yeti
as Yeti
as Yeti
as Yeti
