Inferno is the fourth and final serial of the seventh season of the British science fiction television series Doctor Who, which was first broadcast in seven weekly parts on BBC1 from 9 May to 20 June 1970. The serial remains the last time a Doctor Who story was transmitted in seven episodes. This serial was also the last regular appearance of Caroline John in the role of Liz Shaw.
In the serial, the alien time traveller the Third Doctor (Jon Pertwee) transports himself "sideways in time" to a parallel world, where a British drilling project causes catastrophic amounts of heat and force to be unleashed when it penetrates the Earth's crust.
Plot
The Third Doctor and UNIT are called in to investigate a murder at Project Inferno, an effort to drill through the Earth's crust to harness great energies within the planet's core. It transpires that the drilling is producing a green ooze that transforms all who touch it into savage humanoid creatures called Primords, who can only be killed via extreme cold. Unbeknownst to anyone, the project leader, Professor Stahlman has been infected and is in the early stages of the change. After quarrelling with Stahlman, the Doctor attempts an experiment on the detached TARDIS console, but a freak accident transports him into a parallel space-time continuum.
In this new universe, where Great Britain is a fascist republic, the Doctor is captured and interrogated by Brigadier Lethbridge-Stewart's counterpart, a sadistic, eyepatch-wearing military commandant known as the Brigade Leader, along with the counterpart of the Doctor's companion Liz, who in this universe became a military officer instead of a scientist. When the drill penetrates the Earth's crust it unleashes immense amounts of seismic forces, heat, and poisonous gases, along with more of the ooze, which Stahlman's counterpart, now mutated, uses to transform most of the remaining project staff into more Primords. The Doctor determines that the unleashed energies of the core will eventually disintegrate the planet and is able to persuade the surviving staff members to help him return to his own universe and prevent a similar catastrophe. They eventually succeed in restoring power to the TARDIS console despite repeated Primord attacks, but Liz's counterpart is forced to kill the Brigade Leader when he turns on the Doctor, who narrowly escapes as the Project Inferno facility, and Britain itself, is destroyed by a massive volcanic eruption.
Back in his own reality, the Doctor urgently tries to have the drilling stopped, but like in the other reality his warnings are ignored. This time, however, the slower pace of the drilling means that Stahlman fully transforms into a Primord before the crust is penetrated instead of afterwards, and after the Doctor kills him with a fire extinguisher, the drilling is stopped in time to prevent disaster, saving the human race as a result. Satisfied that the TARDIS console is now working again, the Doctor attempts to depart, only to end up landing in a local rubbish dump.
Production
Scriptwriter Don Houghton was a personal friend of the Doctor Who script editor, Terrance Dicks: they had worked together for Lew Grade at ATV in the 1960s, on the TV soap opera Crossroads. During a train journey, Houghton discussed with Dicks his idea for a serial based on the real life drilling project known as Project Mohole. Budgetary limitations eventually led to the concept of the parallel world, so that the same actors and sets could be used for seven episodes, rather than the four episodes in Houghton's original story breakdown, in order to cut costs.
Despite Douglas Camfield receiving sole credit as director, the studio scenes for episodes 5 to 7 were directed by producer Barry Letts after Camfield had a minor heart attack on 27 April 1970. Letts later stated that Camfield's preparations were so meticulous, he merely followed Camfield's plans for Episodes 5 and 6, but the last episode was largely his own work. Camfield remained credited as director, as BBC regulations at the time forbade Letts from being credited for more than one production role (i.e. as both producer and as director), but, more importantly, Letts did not want Camfield's illness to become widely known lest it harm his career.
Stuntman Derek Ware did not actually perform the stunt in which his character, the mutated RSF Trooper Wyatt, having been shot, falls to his death from the top of one of the chemical tanks, in case he was injured (since he was also needed for the subsequent studio recording). His place was taken by Roy Scammell, who (ironically) also played the soldier who fired the fatal shot. Ware stated in an interview that Scammell had already signed the contract to do the fall before Ware had been cast as Wyatt. At the time it was filmed, it was the highest fall ever performed by a British stuntman.
John Levene's portrayal of Benton as a Primord was inspired by Shakespeare's play Richard III (because of the Primord creature's hump).
Caroline John said she enjoyed her role as Section Leader Elizabeth Shaw, as it was fun playing Liz as a "baddie". She also said she hated doing the scenes in which she was playing her usual role, because it was boring compared to playing the parallel character. She was upset, though, about the scene in which Section-Leader Shaw shot Brigade Leader Lethbridge-Stewart, as she was pregnant at the time. As a result, the scene was recorded with the weapon fired from out-of-shot, after which Shaw was shown returning the gun to her holster. Though her pregnancy has sometimes been cited as the reason John left the show, producer Barry Letts had already made the decision not to renew her contract before learning of it.
During the scenes set on the parallel Earth, images of the British Republic's leader are seen on posters. The image used is that of BBC visual effects designer Jack Kine, in homage to the 1954 BBC adaptation of Orwell's novel Nineteen Eighty-Four in which the face of Big Brother was actually that of the BBC's head of television design Roy Oxley (Kine had worked on the visual effects for that production).
Episode 6 has a small damaged section on the American NTSC videotape which was used as the source of the colour signal for the restoration, which the Doctor Who Restoration Team replaced by recolouring the appropriate section of the b/w film recording.
Locations
The exterior shots used in this production were filmed at Kingsnorth Industrial Estate on the Hoo peninsula, Kent which featured as the setting for the Inferno project.
Music
Director Douglas Camfield chose not to commission any new incidental music for the serial, but instead made use of existing library recordings by members of the BBC Radiophonic Workshop. These included: "Blue Veils & Golden Sands" and "The Delian Mode" (both by Delia Derbyshire); "Battle Theme", "Homeric Theme", "Attack of the Alien Minds" and "Souls in Space" (all by Brian Hodgson); and "Build Up To" (by David Vorhaus). In addition, as was usual, Brian Hodgson supplied new sound effects for the serial, including "Tardis Control On & Warp Transfer".
According to the DVD release notes from the ITV serial Timeslip, this music subsequently featured in the second episode of that show's serial The Time Of The Ice Box.
Cast notes
Camfield cast John Levene as the scripted UNIT sergeant, allowing the character to become that of Benton, who Camfield had cast Levene as in The Invasion (1969). As a result of this decision, Benton was also included in the previous serial, The Ambassadors of Death.
Christopher Benjamin, who plays Sir Keith Gold, subsequently appeared as Henry Gordon Jago in The Talons of Weng-Chiang (1977), and as Colonel Hugh Curbishley in "The Unicorn and the Wasp" (2008). He also played Tardelli in the audio play Grand Theft Cosmos. Most recently, he has returned to play the character of Henry Gordon Jago in a long-running series of audio dramas titled Jago & Litefoot based upon the situation established in The Talons of Weng-Chiang.
The role of Petra Williams was given to Sheila Dunn when Kate O'Mara was unavailable to play the part.
Derek Newark (Greg Sutton) had previously played Za in the first ever Doctor Who serial, An Unearthly Child, in 1963.
Stuntman Alan Chuntz received a bad leg injury in episode 3 when he was hit by the car Jon Pertwee was driving. Pertwee felt so bad about it that he became ill himself, which threatened to disrupt filming.