The people of the planet Skonnos have been promised by an alien calling himself Nimon (voice of Clifford Norgate) that he will restore their past military glory—make them great again—if they will provide human sacrifices and hymetusite crystals, which they can obtain from the nearby planet Aneth. So, they go to war with Aneth. Several shiploads of sacrificial victims have arrived, but the last breaks down in space and the Captain is killed.
The TARDIS is under repair. The Doctor and Romana encounter the Skonnen spaceship transporting the latest consignment of victims. Co-Pilot (Malcolm Terris) demands that the Doctor and Romana repair his ship. When that is done, it moves away, leaving the Doctor stranded in space, but taking Romana to Skonnos. If there is human sacrifice going on, the Doctor’s companion is always in the middle of it. The Doctor bounces the TARDIS off an asteroid in order to follow and continues to repair the TARDIS.
On Skonnos, the leader Soldeed (Graham Croden) notices Romana. Co-Pilot tells him she is a pirate and responsible for delaying the ship and killing the Captain. Soldeed does not believe him but sends both Romana and Co-Pilot into the maze called the Power Complex. The TARDIS arrives and the Doctor is taken to Soldeed, but he soon escapes and heads into the labyrinth himself.
The Nimons are a race of parasites migrating from planet to planet like locusts. They are humanoid, but with the heads of bulls. Once their representative gains trust, they descend upon the planet in great numbers to drain its resources. The Power Complex is fueled by hymetusine and uses a black hole to create a tunnel through space. The walls of the labyrinth shift but always lead to the Nimon. Romana finds the lifeless remains of previous victims. Co-Pilot arrives, pleading for his life, but the Nimon kills him first, then turns his horns on Romana and her friends among the Anethans. The Doctor arrives and distracts the Nimon, saving them, and they follow the Doctor, but the other Anethans are too fearful. With the help of Romana, her friend Seth (Simon Gipps-Kent), K9, and even the disillusioned Soldeed, the Doctor destroys the Power Complex and traps the Nimons on the dying planet Crinoth.
This is obviously based on Theseus and the Minotaur, with the added punch of the plagues of Egypt. Aneth is Athens, Seth is Theseus, Nimon is Minos, and Crinoth is Corinth. Most of the production doesn’t live up to its fascinating classical source. There are a few pluses, however. The Nimons didn’t look that great, but their voices were impressive. Romana is featured strongly, and Lalla Ward plays it straight. She built her own sonic screwdriver, and it was so much better than the Doctor’s that he tried to steal it. Like a lot of Douglas Adams scripts, there are a few too many jokes, but most of Tom Baker’s quips are clearly meant to put his enemies off guard—like Patrick Troughton’s Columbo-like bumbling and Matt Smith’s Robin Williams-like manic monologues. This was the final Douglas Adams script, except for Shada, which never aired. In 2001, he was in talks to write a Doctor Who feature film—four years before the series came back with Christopher Eccleston as the Doctor—when he died of a sudden heart attack after working out for his health. His funeral took place at St-Martin-in-the-Fields Church in London—perhaps the last, best joke for a radical atheist--but an asteroid was named for him and another for Arthur Dent, which is much more appropriate.