Doctor Who: The Darkness of Glass

Set in the Edwardian era, this is a full-on evocation of the Gothic style of the Fourth Doctor's early run, with an isolated island castle that has something sinister skulking in the shadows. The central theme of the story revolves around a magic lantern (that is, an early slide projector, used for entertainment in the days before film), and is something of a cross between Horror of Fang Rock and Tooth and Claw.

The explanation for what's going on is essentially supernatural, and, in many respects, this is a ghost story. There's some variety amongst the castle visitors trapped inside with the monster slowly picking them off, although they might well have been more fleshed out in a longer story. This makes the mystery elements of the tale not as effective as they might be - it's not hard to work out who the villain is, once we know what he's up to. There's also a disadvantage in that the monster is unusually visual for an audio story and would probably work better in a different medium.

Despite these weaknesses, there's some great interplay with the Doctor, and Leela is once again well used, deliberately walking into danger, rather than running away from it. These elements, combined with the Gothic setting, fit it beautifully in with the TV era it's trying to evoke, bringing out both character and atmosphere. As a result, it's a good example of a 4th Doctor story trying to do what his era did best, without laying it on overly strong.