Jon Pertwee
Planet Of The Spiders

Sarah is called by Mike Yates to investigate a group of people after he suspects their meditation is something more sinister. At the same time the Doctor and the Brigadier visit a magic show hosted by Professor Clegg. The Doctor invites Clegg back to U.N.I.T. for experiments in e.s.p.

The meditations that Sarah is investigating form a bridge through which a giant spider is summoned. It jumps onto the back of the ringleader, Lupton. It then orders him to go to U.N.I.T. and steal the blue crystal from Metebelis 3 that Jo has returned to the Doctor.

Lupton steals the crystal, but it is then stolen by Tommy. The Doctor follows Sarah to the Monastery where he finds an old friend K'Anpo. The Doctor learns of Lupton's meditating, and when Sarah is transported to Metebelis 3, the Doctor decides to follow in the TARDIS.

The Doctor finds a plan by the giant eight legs of Metebelis to steal the last blue crystal for their queen, and with it she could become all powerful. The Doctor manages to get hold of the crystal, and he gives it to the Queen. She becomes to powerful and is destroyed. All the other giant spiders die also. The Doctor is damaged from radiation in the Queen lair, and on Earth K'Anpo triggers another regeneration.