He fakes her departure from the retreat, and convinces Tommy, a young retarded man who works there, to keep her presence secret. Sarah and Mike hide in the cellar, and watch Lupton's group as they summon an enormous spider, which attaches itself to Lupton's back and disappears. The Doctor and the Brig have been attending a variety show, and The Doctor convinces a mentalist named Clegg to assist in his experiments on psychic potential. The Doctor gave to Jo Grant. Jo has returned the gift because it frightened the Amazon natives she and Cliff Jones have encountered.
Clegg looks into the crystal, and dies of fright.
Sarah arrives and tells The Doctor about the center, and he's intrigued by the spider, since Clegg's last words concerned spiders. The spider determines the crystal's location, and Lupton comes to UNIT HQ and steals it. He leads The Doctor, Sarah and the Brig on a long chase before he disappears, materializing back at the center. Tommy, who has a fondness for shiny objects, steals the crystal. The Doctor and Sarah arrive, and while The Doctor talks with Cho-Je, Sarah overhears plans for another ceremony, and tells Tommy to alert The Doctor.