This one I've seen before, and I absolutely love it. It's one of the all-time greatest companion departure stories; the plants it seeds in the narrative to pay-off in the climax is so cleverly done, such as the scene where the Doctor speaks of how an asteroid destroyed the dinosaurs, or him telling Adric he doesn't want him 'plotting a course to his own destruction'. This is such slick screenwriting from somebody who by this point was relatively new to writing Doctor Who.

Nyssa doesn't get much to do in this story  but that doesn't matter here. Because this is more about the Doctor and Adric, and their relationship, and in that department the story absolutely excels. We learn more about the dynamic of these two, and their almost familial squabbling.

Of course, you can't talk about Earthshock without discussing the Cybermen, and this is one of their best stories for sure. They have a great design in this story, and unlike the previous Cyberman serial to this one, Revenge of the Cybermen, they actually feel like Cybermen here. There's no weird emotional Cybermen here, and Peter Davison's Doctor gets an amazing speech that perfectly explains what separates the Cybermen from humanity: 'When did you last have the pleasure of smelling a flower, watching a sunset,eating a well-prepared meal? For some people small, beautiful events are what life is all about!"

This would be an amazing Cyberman story even without Adric's tragic exit. It's exactly how to do a Cyberman story.

This story also features a fantastic guest appearance from Beryl Reid, as the captain of the space freighter . She's probably one of the classic series' greatest guest turns, and has such a presence on-screen alongside the TARDIS crew of Season 19.