Unfinished and unbroadcast due to a writers' strike, this 6-part serial was later put together as one release, using some new material, the material originally shot, and Tom Baker's narration covering the scenes never filmed. The result is that we get to see a serial that is better than the one that actually closed out season 17, but has many of the issues associated with the show throughout this season.
The title references a prison used by the Time Lords, but forgotten by them all; it is the subject sought by Skagra, by way of a book held by a Cambridge Professor (and Time Lord). The Doctor comes to him just in time to try to intervene in Skagra's plan to find the prison and use his mind extraction device to take the knowledge and being of all the criminals there, thus making him immensely powerful (although it is a shame he never extracted anything from someone who knows how to dress). In the background are monsters, in the foreground there is humor, and the plot is decent enough.
This version benefits from being shorter due to the unfilmed scenes, because 6 full episodes does feel a lot for this material. The ideas are decent enough, and it does have some good cliff hangers, but it is stretched a bit too thin for what it does, and doesn't maximize on many of the ideas. The monsters of the piece look cool as a piece in the museum where the narration is set, however in their brief appearance in the filmed scenes, they come over as another lumbering man in a suit. Likewise the orb is all a bit silly as a threat. The production is mostly set in the Professor's flat, and on location around Cambridge - it is a shame that the remainder wasn't shot, but to be fair, given the production standards in this season, it looks better described by Baker rather than seen.
The cast are solid and enjoyable through. Adams' writing is a bit messy in the way it mixes in silly jokes that don't work that well, interesting dialogue scenes and characters, but is not as smart as I hoped. Probably Shada's reputation benefits from it being unfinished and unbroadcast; while it is better than the actual season finale (Horns), it still fits into the standard of season 17 even if it is decent enough.
