Ghost Light
Ghost Light has always been one of those Doctor Who stories that you wouldn't be ashamed to show your friends. It has a certain respectability: atmospheric, well-acted, ironic, compelling. Good TV, plain and simple. Looking at it now, in 2003, I can't find any reason to change my opinion. There's the odd flaw, often related to haste or lack of time (as when a piece of dialogue is spoilt by an obtrusively abrupt cut in the the Reverend Ernest Matthews introductory scene). But this sort of tiny technical flaw is part of what makes Who so endearing; it's not enough to spoil an excellent story.
The plot itself is, as is often noted, a little opaque. One reason for this is that much of the dialogue (in the first two episodes at least) doesn't actually provide a lot of explanation as to what is going on - unusually for Doctor Who, there isn't a great amount of expository writing. There are enigmatic conversations (such as that between the Doctor and Isiah), bewildering monologues (Fenn-Cooper's, in episode one, is superb), and much else that is strange and perplexing (in a good way), but we, the viewer, are left to fill in many of the gaps.
We may have to watch Ghost Light a couple of times to appreciate it fully, but when a story is so full of brilliant moments, it isn't really a hardship. There is Ace's analysis of the 19th century mind: "Scratch the Victorian veneer, and something nasty will come crawling out!"; the Reverend, firmly against the theory of evolution, de-evolving into an ape-like state, munching a banana; and the iconic moment where the Doctor is told, after he stops a clock by halting the movement of the pendulum, that he is as "powerful" as he is "wise". Even writing about it makes me smile. Ghost Light takes Doctor Who and makes it better; takes two characters, and makes them finer and more complex.
The New Adventures told stories too broad or deep for the screen, and here Platt plants seeds for what would follow: a Doctor with dark motives and agendas - "Even I can't play this many games at once!" - and an Ace tormented with memories, looking on as a building burns, emergency-service lights flashing in her face. Highly recommended, and definitely worth revisiting.