Some fifty years after the "Doctor" (now Jon Pertwee) helped the King of "Peladon" lift a terrible curse, he and "Sarah Jane" (Elisabeth Sladen) return to it's citadel to find the new queen (Nina Thomas) being controlled by her chancellor "Ortron" (Frank Gatliff) and facing a rebellion from her oppressed mineworkers who are fed up being used as glorified slaves. Added to her misery is the fact that the planet is caught up in some intergalactic furore over that which they are mining - a rare mineral called "Trisilicate" that only exists on "Peladon". Thanks to the help of the miners' leader "Gebek" (Rex Robinson) and of ambassador "Alpha Centauri" - replete with one big eye and attired in a very 1970s shower curtain, the visitors must discover the mysteries of the monstrously lethal "Aggador" and fend off the invasive "Federation" before the kingdom is subsumed and everyone is reduced to servitude. It's a six-parter, this one, but the story is just too strung out to work well. The last pair of episodes do bring things to an head a bit more entertainingly but the pair leaping constantly from frying pan to fire does repeat itself a bit too often amidst just a little too much painted papier-mâchê. It's OK, but entirely forgettable.