Episode 96, Underworld, is a decent enough Doctor Who DVD. The story is a bit thin and budget constraints stretch out certain scenes. It is also the BBC's first attempt at blue screen so it sometimes looks as cheesy as a low budget monster movie from the fifties and sometimes rather Flintstones like as characters run past the same two or three rocks time and again. Doctor Who fans are used to the low budget constraints of this classic BBC science fiction show so that is not a problem for them.
The Doctor and Leela crash onto a Minyan ship. The Minyan are a race that disappeared 100,000 years ago. These last Minyan are on a quest to find P7E, the ship that carries the computer with all their genetic information. If they can do that, the Minyan race can be reborn -though how is not really explained. The Minyan ship crashes into the core of a forming planet where some people are slaves working in mines in a society dominated by something called the Oracle.
The Minyan ship's small crew and the Doctor and Leela go exploring the seemingly many but only three tunnels of the mine. They get to the planet center and discover something interesting after helping in a minor miner revolt.
The ending is kind of neat in terms of science fiction story standards.
There is a lot of running around in tunnels in Doctor Who Episode 96 Underworld. This is done through blue screen work. Back in 1978 blue screen was not the most perfected technology, especially at the BBC, so you more often than not see that the actors' images are superimposed on a visual. This often gives the impression they are running on nothing.
Special features on this Doctor Who DVD include a commentary track with Tom Baker, Louise Jamieson, and writer Bob Baker; Into the Unknown, a thirty minute making of; subtitled production notes; and a photo gallery.