4 May 1974
Nicholas Courtney (Brigadier Lethbridge-Stewart) [1-2, 6], Richard Franklin (Mike Yates), John Levene (Sergeant Benton) [1-2], Cyril Shaps (Professor Clegg), John Dearth (Lupton), Christopher Burgess (Barnes), Terence Lodge (Moss), Carl Forgione (Land) [1-2, 4-6], Andrew Staines (Keaver) [1-2, 4-6], Kevin Lindsay (Cho-je) [1-3, 5-6]‡, John Kane (Tommy), Chubby Oates (Policeman), Pat Gorman (Soldier), Terry Walsh (Man with Boat)], Michael Pinder (Hopkins), Stuart Fell (Tramp), Ysanne Churchman [2-6], Kismet Delgado [3-6], Maureen Morris [3-6] (Spider Voices), Gareth Hunt (Arak) [3-6], Geoffrey Morris (Sabor) [3-5], Jenny Laird (Neska) [3-5], Joanna Munro (Rega) [3-5], Ralph Arliss (Tuar) [3-6], Walter Randall [3-5], Max Faulkner (Guard Captains), George Cormack (K’anpo)
|Written by||Robert Sloman|
|Directed by||Barry Letts|
|Produced by||Barry Letts|
The blue crystal that The Doctor took from Metebelis III in a previous adventure is desperately sought by the Eight Legs, a race of mutated spiders, as the final element in their plan for universal domination. With help from an old mentor, The Doctor realises the only way to foil the plot is to make the ultimate sacrifice. The Doctor must risk death to return to the cave of the Great One and save the universe.
Parts of this story were recorded at the same time as parts of Robot. This not only meant that Jon Pertwee and Tom Baker were literally playing The Doctor at the same time, but also that Elisabeth Sladen“, and to a lesser extent, Nicholas Courtney and John Levene“, were having to rush back and forth between the two productions.