The use of caves also gives a claustrophobic feel that serves Earthshock well -- we get narrow passages and effective lighting, with lots of shadowy figures and such. It's so good, in fact, that it's a bit of a letdown to shift to the by-now-standard TARDIS interior establishing scenes. Adric, it seems, feels unappreciated, so he and the Doctor have a fight about it, one which leads the Doctor to storm off into the cave system that the TARDIS has just materialized in. I understand why the production team wants to add these more "soap opera" elements, and while I like the idea of having a sense of continuity, to show the interpersonal relationships between the main characters, I feel like squabbling isn't the way to go about it. I want to like the main characters, I really do, but things like Tegan's constant sniping and Adric's repeated petulance make it really hard to.
Still, it does settle down after a bit, and the business with the troopers in the caves is more than enough to paper over any problems with the other scenes. This is also a fairly gruesome episode; while we don't actually see troopers being killed by the mysterious androids wandering the caves, we do see the aftermath of steaming goo and ruined uniforms -- it doesn't look like it was a pleasant death. And once the Doctor, Nyssa, and Tegan are introduced to the main action (complete with the usual suspicion regarding their presence in places where people keep disappearing), things really start moving. And then that cliffhanger, where we see that those strange androids are being controlled by... Cybermen! What a surprise that must have been to the initial viewing audience, to see the return of the Cybermen not just after seven years, but also without any sort of advance publicity whatsoever (Nathan-Turner in fact turned down the chance at a Radio Times cover -- which the show hadn't had since 1973 -- to preserve the surprise).120 All these factors combined mean that Earthshock Part One is one of the best episodes the show has ever produced.
The high standards continue in part two, with some frantic scenes of the troopers fighting off the androids as well as the Doctor trying desperately to defuse a bomb before it's exploded by some unseen force (aka the Cybermen, but the Doctor doesn't know that yet). Oh, and we get our first use of the phrase, "Brave heart, Tegan," by the Doctor. There's also the nice use of old clips to remind viewers of previous Cybermen stories (even if it also serves as an indication of the state of the archives by this point, as the Cyberleader describes the events of The Tomb of the Cybermen (then missing) but uses a clip from The Wheel in Space to illustrate the second Doctor). And the redesigned Cybermen are fantastic-looking (and in fact are my favorite Cyberman design), a sleek mix of parts to suggest a powerful cybernetic organism -- and I love the transparent jaw, with the silver chin that can be glimpsed moving inside.
Soon the action moves from caves to a freighter heading toward Earth, and things do start to get a little silly. No, I'm not talking about Beryl Reid as the freighter captain (at this point in the story she seems in control of events and totally competent), but rather about the fact that three crewmembers have vanished without trace and yet only one crewmember, Ringway, seems remotely concerned about this. Let's be clear: three crewmembers have disappeared, and almost no one cares. What's wrong with these people?
And, of course, two more crewmembers are offed while the Doctor and Adric are exploring the cargo hold, and their timing is unfortunate enough to be discovered by Ringway as they're examining the bodies. "On this ship we execute murderers," he declares, pointing a gun at them...
120 Although there's no ratings surge to suggest that people were interested -- the next episode, shown the following day, had lower ratings than part one. Parts three & four were up a bit though, so maybe it just took some time for the news of the Cybermen's return to circulate.