7A. The Mysterious Planet

Season Twenty Three - 1986 (The Trial of a Time Lord)

Script Editor: Eric Saward
Produced by: John Nathan-Turner
Writer: Robert Holmes
Director: Nicholas Mallett
Designer: John Anderson
Incidental Music: Dominic Glynn

I am the Lord President of Gallifrey. You can't put me on trial.


The TARDIS is drawn to a huge space station. Only the Doctor emerges, and he is unsure where he is. There is only one door to choose from - the door to a huge courtroom where a huge jury is sat. As he watches other figures enter which are announced as an Inquisitor and his prosecutor - the Valeyard. So begins the trial into the Doctor's interference into the affairs of other people and planets:

The first piece of evidence in the prosecution is the Doctor and Peri's visit to Ravalox.

The Doctor comments to Peri that the planet has almost exactly the same mass, angle of tilt, and period of rotation as Earth. But it is almost two light years from Earth, and has been ravaged by solar flares.

A group of people had survived in an underground city ruled by a robot. It had been programmed to keep an equal and stable society. If there are too many people present they are culled, alhough one of the guards disobeyed the orders and often allowed them to escape to the surface which is now safe from solar flares.

On the surface a very different society is emerging. The Doctor and Peri are captured by the villagers, and so are two crooks Glitz and Dibber, who are intent on destroying the villagers ' Great Totem' that they claim is a navigational beacon.

They do eventually destroy the beacon, which the Doctor finds out is Drathro's, the robot which controls the underground dwellers, black light power source. With it destroyed the planet faces a black light explosion which could threaten the entire Universe. The Doctor manages to limit the explosion to Drathro's lair, destryoing the robot in the process.

Regular Cast

  • Peri Brown: Nicola Bryant

Guest Cast

  • The Valeyard: Michael Jayston
  • The Inquisitor: Lynda Bellingham
  • Sabalom Glitz: Tony Selby
  • Katryca: Joan Sims
  • Dibber: Glen Murphy
  • Merdeen: Tom Chadbon
  • Voice of Drathro: Roger Brierley
  • Broken Tooth: David Rodigan
  • Balazar: Adam Blackwood
  • Grell: Timothy Walker
  • Humker: Billy McColl (2-4)
  • Trandrell: Sion Tudor Owen (2-4)
  • Drathro Operator: Mike Ellis
  • The Jury: David Backe, John Buckmaster, Rodney Cardiff, James Delaney, David Eynon, Peter Gates Fleming, Gary Forecast, Leslie Fry, Bob Hargreaves, Johnny Lee Harris, Jack Horton, Lew Hooper, Derek Hunt, Guy Matthews, Ken Pritchard, Roy Seeley, John Shereton, Kenneth Thomas, Leslie Weeks, Geoff Whitestone, David Wild, Llewellyn Williams
  • Train Guards: John Emms, Mark Kirby
  • Warriors: Richard Aldridge, Robert Bicknell, Peter Dukes, Paul Ellison, John Emms, David Hampston, Christopher Holmes, Mark Kirkby, Paul Lecomber, Oscar Peck, Rhett Stevens, David Wild

Original broadcast on the BBC

Channel Title Date Viewers Rating
BBC 1 640. Part One Saturday, September 6, 1986 5:45 PM - 6:10 PM 4.9M 72%
BBC 1 641. Part Two Saturday, September 13, 1986 5:45 PM - 6:10 PM 4.9M 69%
BBC 1 642. Part Three Saturday, September 20, 1986 5:45 PM - 6:10 PM 3.9M 70%
BBC 1 643. Part Four Saturday, September 27, 1986 5:45 PM - 6:10 PM 3.7M 72%


  • Television Centre Studio 3
  • Television Centre Studio 6

Outside Locations

  • Butser Ancient Farm Project, Pidham Hill, Hants
  • Queen Elizabeth Country Park, Gravel Hill, Horndean, Hants


Part 1: Peri's accent appears to be slipping: she pronounces 'fireball' and 'sterile' in an English accent.

Part 1: At the end of this episode a stone hits the Doctor too soon. He was supposed to be stoned for a little while before being hit, but one overzealous extra hit him too soon. (This was a blooper Colin Baker mentioned at a convention)

Working Titles

The Robots of Revelux

The Robots of Ravalox


The first episode sees the debut of a new arrangement of the theme tune by Dominic Glynn.

Although the whole season was shown on television as one long 14 part story there are four segments with production codes, and the programme has been novelised in this form.