But even if you did remember the Silurians from their eponymous 1970 story, you might wonder what's happened to them since then -- their third eye now flashes whenever they speak (just like a Dalek), and their voices sound almost identical to the current Cyberman voices. And their behavior doesn't really distinguish them from the Cybermen either -- at least not at this point in the story. They're there instead to provide some excess paranoia for the already paranoid crew aboard Sea Base 4, and to unleash their troops upon the base -- but that won't happen until the end of part two. The Sea Devils look and sound rather better, even if they're wearing some sort of armor instead of blue string vests and their necks seem to be really fat (because that's where the performer's head is).
In the meantime we've got that incredibly paranoid crew to deal with -- writer Johnny Byrne is clearly intending for this story to be an allegory for then-current events (note his choice to set the story exactly 100 years in the future, in 2084), although wisely he doesn't identify the two opposing sides, other than that they're set against each other and that tensions are high. Still, it's clear we're meant to draw parallels between the United States and the Soviet Union. But that said, there are some typical melodramatic elements: Doctor Solow and Nilson, for example, are enemy agents aboard the Sea Base, but for all the subtlety they exhibit they might as well be wearing signs indicating their status -- yet no one seems to notice. Of course, the base's crew is also relying on an untrained student to man their missiles, and no one seems terribly concerned when he exhibits clear signs of a mental breakdown. (And incidentally, the graphics used to indicate the missile run are terrible -- they're barely even up to Missile Command's standards.)
And into this environment the Doctor, Tegan, and Turlough are inserted, where they get to also behave oddly (the Doctor, for instance, decides to create a diversion by overloading the base's nuclear reactor -- this is after he wanted to announce his presence to the base and then changed his mind). There is a great moment where he gets the base's crew to begin to trust him by handing over the weapon he's pointing at them -- but these moments are rather thin on the ground. There's also the part where the Doctor recognizes the Silurian ship (the underwater model sequences, at least, are very well done), and we get an incredibly quick summation of who they are -- "The race that ruled this planet long before your species evolved", and then later, "They're honourable. All they ever wanted to do was live in peace", which doesn't exactly match what we saw in the '70s -- before their assault begins.
While that Silurian assault begins by the end of part two, there's not really much to mention here, other than we get our first look at the giant monster the Silurians send in: the Myrka. It's not too bad when it just has to stand there and look menacing -- it's certainly a hell of a lot better than the incredibly stupid-looking foam rubber bulkhead door that falls on Tegan -- and the "electrical death via touch" is handled decently too. The cliffhanger's a bit generic though; the Doctor and Tegan are trapped on the same side of the bulkhead as the Myrka, with Turlough on the other side. Wonder how they'll get out of this one...