You know, when you need to account for all the members of your crew, it helps if you know how many people are on your crew.
Basically, Adric, don’t be a stowaway.
So, we have one of the three rulers of the planet have cornered the Doctor and Romana in an underground chamber. And the Doctor surprises the man by…guessing his original name and that he’s a lot older than he looks.
Yes, the man is a vampire.
And he does try hypnosis, but that doesn’t work if you’re smart enough to cover your eyes, and since these are Time Lords we’re talking about, of course they’re smart enough.
Fortunately, someone comes along to help. A rebel named Tarak shows up. He used to be a guard, so sneaking in is easy. He tosses a stone (or plaster) column at the vampire, knocking the fellow out and allowing the Doctor and Romana to escape. Now, Romana does remember her time in the Academy, and there was some information on vampires there as it relates to the first Time Lord, the mighty Rassilon. But you’d need a really old computer to have that information.
Fortunately, the TARDIS is very old. Unfortunately, Tarak mentions Adric is in the castle, and this is the first the Doctor or Romana knew Adric was even with them at all.
Always tell people where you’re going, folks.
Anyway, the Doctor knows the TARDIS well and heads back there to do some research, leaving the rescue of Adric to Romana and Tarak.
There are different levels of success there. The Doctor, working with K9, does eventually find out there was some kind of Prime Vampire monster at some point. Rassilon and the Time Lords fought the guy and eventually defeated them with “bowships,” whatever they are. Some more research says vampires are immune to energy weapons, so it sounds like the way to beat them is with a flying stake of some kind through the heart.
So, that’s something.
On the other hand, Romana and Tarak do find Adric, but he’s asleep or mind whammied or both in the same room the other two vampire lords are sleeping in. Waking Adric also wakes them, and they easily kill Tarak. And since the blood of a dead man doesn’t do them any good, well Romana and Adric are right there.
I hope the Doctor shows up soon with a bowship…whatever that is.