"State of Decay" tips its hand pretty early, but the way the pieces come together with a healthy dash of continuity makes this a fun episode. The Doctor and Romana continue to explore the green-tinted E-Space, and we get a name for our regular non-E-Space universe - N-Space. K-9 (have I mentioned how much I love K-9?) picks up a planet on the edge of his scanners with a surprising amount of technology for the amounts of energy being emitted. Basically we have high tech toys in the dark ages, complete with a trio of rather gaunt-looking royalty. We meet the royal trio, as well as the peasants on this planet during some sort of ceremony which reminded me of a cross between "The Lottery" and a buffet line.
When the Doctor and Romana land, its not long before they're grabbed by the rebels who are pro-science, pro-knowledge and so obviously the good guys. Apparently knowledge is forbidden on this planet. Meanwhile, Adric ducks out to look for the Doctor and Romana and promptly gets himself grabbed by one of the trio of royalty we met earlier - Aukon. Aukon wants him to be one of the 'chosen ones'. By know, you probably know where we're going with this.
The Doctor and Romana just HAVE to meet these guys, so there's some sizing up between the other two royals and the Time Lords, and sure enough, Romana slightly cuts her finger. They seem VERY interested in her blood. Yep, vampires.
To be fair, this is Who doing vampires WAY before it was 'cool'. So the questions we're left with are: why vampires? Why the weird disparity between the level of tech on this planet and the apparent level of cultural development? Will our heroes ever escape the questionably-colored pocket universe known as E-Space? Probably with the next story, since everything I've read on Wiki calls it "The E-Space Trilogy"
Oh, and Adric? Kind of a dick this episode.