Whilst the "Doctor" (Jon Pertwee) and the "Brigadier" (Nicholas Courtney) are doing some experimentation with a scientist with strong clairvoyant skills, "Capt. Yates" (Richard Franklin) manages to interest "Sarah Jane" (Elisabeth Sladen) in some curious goings on at a country retreat run by a kindly old Buddhist. Of course, the two topics soon become one as those doing the meditation manage to tap into some intergalactic spiders whose aim is to find a missing blue crystal - that the "Doctor" has had for years - so as to augment the power of their supreme leader and enable her to rule the cosmo... read the rest.