Last updated 30 October 2022

Doctor Who: Castrovalva


Story Number: 116 (5Z)
No of Episodes: 4

Writer: Christopher H Bidmead
Director: Fiona Cumming
Producer: John Nathan-Turner

Starring: Peter Davison, Janet Fielding, Sarah Sutton, Matthew Waterhouse, Anthony Ainley

BBC One (United Kingdom):
First Broadcast: Monday 4th January 1982 - Tuesday 12th January 1982
Running Time: 1 hour, 36 minutes, 14 seconds

Average Audience: 9.57 Million   

Chased by the Pharos Project’s security chief (Dallas Cavell) and two guards (Harry Fielder, Kenneth Lawrie), Nyssa, Tegan and Adric help the newly regenerated Doctor towards the TARDIS. The Doctor collapses and they are caught as a Sussex Area Health Authority ambulance drives up. The ambulancemen (David Ellis [not seen on screen], Derek Matt, Peter Roy) load the Doctor into the back of the vehicle. While Adric distracts the guards, Tegan and Nyssa drive off in the ambulance. They arrive at the TARDIS and get the Doctor inside. Watching on the TARDIS’s monitor, Nyssa sees the Master’s TARDIS appear, still in the shape of an ionic column. Force rays are emitted from it which knock everyone out. Then it dematerialises leaving Adric behind. Nyssa and Tegan help Adric into the Doctor’s TARDIS. 

The Doctor is wandering the TARDIS’s corridors and comes across a room full of cricket paraphernalia. He changes his clothes into cricketing whites and an Edwardian beige coat and a hat that he finds hanging by a mirror outside the room. His regeneration is, however, failing and he enlists Nyssa’s and Tegan’s help to find the zero room, described as a neutral environment cut off from the rest of the universe. 

Once inside the zero room, the Doctor levitates and settles down to sleep. Suddenly an image of Adric appears on the wall. He warns Nyssa and Tegan that they are plunging into a trap. 

The trap has been set by the Master who is holding the real Adric captive while a false image of the boy is loose on the TARDIS. The image has sent the ship plunging back to Event One – the hydrogen in-rush that preceded the big bang at the creation of the universe. The Doctor recovers sufficiently to show Tegan how to eject rooms from the TARDIS and thus create thrust which will push them away from the explosion. She jettisons the rooms and they escape unscathed. Unfortunately, one of the jettisoned rooms was the zero room and all that remain of the stable environment are the doors. Nyssa fashions these into a coffin-like casket in which to carry the Doctor. 

Tegan meanwhile has found an entry in the TARDIS data bank describing the ‘dwellings of simplicity’ on Castrovalva, a place that has properties similar to those of the missing zero room. It is a small planet of the Phylox Series in Andromeda. 

Arriving on the planet, Nyssa and Tegan transport the Doctor towards the dwellings, which are on top of a massive cliff. There they meet Ruther (Frank Wylie), Mergrave (Michael Sheard) and Shardovan (Derek Waring) who offer them rooms and hospitality. They also meet the Portreeve, a person of importance and wisdom who seems to know who the Doctor is, despite the fact that the Doctor isn’t sure himself. 

The Portreeve is, in fact, the Master (Anthony Ainley), who has engineered Castrovalva using Adric’s skill at mathematics and the power of block transfer computations. The entire place is a trap for the Doctor, who eventually realises the deception through study of the Castrovalvan history books, which are 500 years old but tell the planet’s history up to the present day. 

The Doctor reveals the trapped Adric behind an apparently magical tapestry which shows changing images. The boy is held in a web of hadron power lines but Shardovan, exercising his free will, swings down on a chandelier and smashes the web. As Castrovalva starts to fold in on itself, the Master tries to escape in his TARDIS, now disguised as an ornamental fireplace, but cannot. The Doctor, Nyssa and Tegan are led to safety by a recovered Adric who, as the creator of the world, can see the way out. Mergrave stays behind to impede the Master’s escape. 

The doors close behind the Doctor, Tegan, Nyssa and Adric, trapping the Master beneath a pile of fighting, struggling Castrovalvans. 

The quartet of time travellers return to the TARDIS where the Doctor places a stick of Castrovalvan celery on his coat lapel.

Synopsis from Doctor Who: The Fifth Doctor Handbook by David J. Howe, Mark Stammers and Stephen James Walker, reprinted with permission; further reproduction is not permitted. Available from Telos

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