Thing T. Thing sports mind-bending bling, leading to the dramatic exit of companion Sarah Jane Smith
A spaceship on a string flies into view as we learn of the impending obliteration of silicon-based despot, Eldrad. Cut to 150 million years later on the other side of the universe. The time is nowish. The place is a quarry in England. But this time, it actually is a quarry, and The Fourth Doctor and companion Sarah Jane Smith have just materialised in the TARDIS as a pile of rock is about to be exploded on top of them.
The detonation somehow unearthed a disembodied hand, don’t you know, and it turns out to have once belonged to that Eldrad fellow. It’s missing a finger but sporting some powerful, mind-bending bling, and now takes over Sarah Jane, compelling her to feed it nuclear power in order to regenerate the megalomaniac from the wrist up.