Inferno was the fourth and final story of Season 7 of Doctor Who. It was the last story to feature Caroline John as companion Liz Shaw (although her departure is not depicted). It was also the first Doctor Who story to explore the concept of parallel universes.
UNIT are providing security cover at an experimental drilling project designed to penetrate the Earth's crust and release a previously untapped source of energy. Soon however the drill head starts to leak an oily green liquid that transforms those who touch it into vicious primeval creatures with a craving for heat. The Doctor is accidentally transported by the partially repaired TARDIS control console into a parallel universe where the drilling project is at a more advanced stage and, thwarted by his friends' ruthless alter egos, he works to save both universes.
The Inferno Project is the nickname given to a project to penetrate the Earth's crust to obtain pockets of Stahlman's Gas at its core, which is theorized to be able to provide endless, massive amounts of energy. Professor Stahlman himself is ill-tempered and obsessive about any interference with the progress of his work. Sir Keith Gold, the project's executive director, is concerned about this and tells Petra Williams, Stahlman's assistant, that he has called in Greg Sutton, an oil drilling expert, to consult on safety issues. UNIT is overseeing security at the project, and the Doctor is at the facility for his own reasons. He is using the output of the project's nuclear reactor to power experiments on the TARDIS console, which has been made portable, in an attempt to end his exile on 20th century Earth imposed upon him by the Time Lords.
The project, however, has its own problems. Slocum, a worker repairing one of the drill pipes, encounters a toxic green slime seeping out of one of the output pipes. Upon contact the substance rapidly mutates him into a feral creature, which goes berserk and kills one of the other workers. While the Brigadier and Sergeant Benton investigate, the Slocum creature enters the reactor control room and attacks Bromley, the technician there, then pushes the reactor power to maximum.
At this time the Doctor is using the TARDIS console and the energy rush shifts the console and the Doctor into a dimensional void from which he is barely saved when Liz manages to cut off the power flow. Alarms go off as the drill is in danger of shutting down due to the overload. When the Doctor reaches the reactor control and starts to lower the power output, Slocum bursts through a door, into the room, ready to kill....
The Doctor tries to calm Slocum down while he screeches horribly but a UNIT soldier, Wyatt, tries to shoot Slocum and is attacked. Slocum eventually collapses, as does Wyatt, and the former's body is so hot that it scorches the wall where he falls. The Doctor voices his concern that Slocum's mutated form seems to be filled with some strange power. He has also heard the screeching before — during the 1883 explosion of Krakatoa. Benton informs the Brigadier that Bromley and Wyatt have gone missing, before their medical checkups. The Doctor encounters Wyatt, who is in the process of mutating, on the cooling towers. Wyatt falls from it, to his death, but the Doctor does not notice the mutated Bromley on the tower as well.
The drill has been bringing up more quantities of the green slime, but Stahlman dismisses any connection between that and the incidents at the project. When a jar of the slime starts to bubble over, he quickly grips it, superficially burning his hand. Stahlman places the jar in a box which he orders frozen, and secretly sabotages the project computer, by stamping on the computer's micro-circuit, which was predicting disaster. He also orders that the power be cut off to the Doctor's hut, so that the drilling can be accelerated, with penetration occurring in 49 hours. The Doctor, in the meantime, sends Liz away on a wild goose chase while he hooks up the console again. Noticing the power drain, Stahlman cuts the power to the console just as Liz and the Brigadier rush back to the hut. As they look on, the Doctor, his console and his car, Bessie vanish, into thin air...
Liz tells Stahlman he must restore power to the Doctor's hut, but the Professor is indifferent.
The Doctor wakes up apparently still in the hut, but when he drives away in Bessie he is shot at by soldiers including Benton. Just as he believes he has shaken off pursuit, he encounters Liz dressed as a soldier and is captured by her and taken to the Brigadier for questioning - but none of the people encountered are the people he knows, as the Doctor quickly deduces that he has travelled to a parallel universe. On this world, a Republic of Great Britain exists, and is run by a fascist regime after the execution of the Royal Family, possibly in 1943. The Inferno project is also ongoing, and is slightly more advanced, but the security is provided by Brigade Leader Lethbridge-Stewart, a sinister man with an eyepatch, Section Leader Elizabeth Shaw, and Platoon Under Leader Benton, all of the Republican Security Forces, that world's counterpart to UNIT. The Doctor is assumed to be a spy because of his knowledge of the project. When an emergency with the pipes develops he tries to lend a hand, but he is caught by Benton, who threatens him at gunpoint, with the words 'Are you coming with me or do I shoot you here and now'.
It is only with the Doctor's help that the crisis is averted, but he is interrogated and thrown into a cell regardless. He tries to convince the parallel versions of his friends that he is from another universe, but they believe he is trying to feign insanity. Here, Stahlman has also been infected with the green slime, and is mutating. The Doctor is placed in a cell with a sedated Bromley, but the alarm is raised when Bromley awakens fully mutated. Escaping, the Doctor makes his way to the main control room to stop the drilling but is discovered. The Doctor pleads for them to stop, telling them that the screeching is the sound of the planet "screaming out its rage,", with Stahlman holding him at gunpoint, with the countdown at 1 second before penetration...
As Stahlman holds a gun on the Doctor, penetration is achieved, an explosion is heard and an earth tremor rocks the installation. The temperature rises rapidly as more green slime oozes out of the cracked pipes. As the Doctor and the parallel Sutton try to contain the explosion, Bromley attacks them. They manage to escape, leaving Stahlman behind a heat shield with the bodies of the unconscious workers. Stahlman rubs the slime on their faces, mutating them as well. There are seismic disturbances all over the country, and the Doctor explains that now that the crust has been penetrated, the planet will soon revert back to the gases it sprung from, saying they have "reached the point of no return," and that they will never be able to plug the hole, as nothing can withstand the immense pressures of the mantle.
The Doctor tries to convince the others that he can stop this from happening in his own universe if they will help him to return, and shows them the TARDIS console. The Brigade Leader demands that the Doctor save them, too, but the Doctor says that they do not belong in the other universe. Refusing to accept this, the Brigade Leader orders everyone back to the control room, where Stahlman and his fellow mutants attack, infecting Benton as well… In the office, The Doctor starts to explain his plan, but one of the arms of the Primords break through the glass...
Finally agreeing to help the Doctor, the group fights their way out using fire extinguishers to paralyse the mutants. By this time, the sky has turned red and the heat is overwhelming. The parallel Petra Williams, with Greg Suttons help, manages to feed power to the TARDIS console. At the last moment, the Brigade Leader snaps and threatens to shoot the Doctor if he doesn't save them, but is gunned down by Section Leader Shaw. As a wall of lava sweeps towards the hut and the others watch the end coming towards them…
Meanwhile, back in the Doctor's universe, Sir Keith is on his way to the Ministry to recommend an inquiry into the Inferno project, as he believes Stahlman is being reckless in his handling of the project. Unfortunately, the car he is in crashes (Sir Keith's counterpart was in fact already dead by the time the Doctor arrived in the other universe).
The Doctor is back but unconscious in a healing coma, and there are only three hours left before penetration zero. When he awakes, the Doctor goes to the main control room and tries to smash the controls. He is unsuccessful and has to be restrained, but manages to tell Liz to put a new circuit into the computer that Stahlman had sabotaged. Liz does so, and the computer advises drilling be stopped at once. In the meantime, Stahlman orders everyone out of the drill head area, then when they are gone he picks up a handful of slime and rubs it into his face, causing himself to completely mutate. The Doctor escapes from the sickbay and returns to the control room, dealing with the Bromley mutant on the way. The Stahlman mutant emerges and has to be subdued with fire extinguishers. With seconds to go, the drill is shut down and the shaft filled in.
Later, Sir Keith, who suffered only minor injuries in the crash, informs the Doctor that the project is being abandoned and everyone is leaving. The Doctor announces that he, too, is leaving. The Brigadier and Liz protest, and the Doctor sharply tells the Brigadier that he reminds him of his fascist counterpart. The Doctor activates the console and vanishes; on this occasion, Bessie is left behind. A few minutes later, the Doctor appears at the door of the hut, with mud on his clothes – having only made it as far as a nearby garbage dump! Suitably chastened, he asks the Brigadier to help him retrieve the console, which has landed in a somewhat inaccessible position, much to Liz's amusement.
- The Doctor — Jon Pertwee
- Liz Shaw / Section Leader Liz Shaw — Caroline John
- Brigadier Lethbridge-Stewart / Brigade Leader Lethbridge-Stewart — Nicholas Courtney
- Sergeant Benton / Platoon Under Leader Benton — John Levene
- Professor Stahlman / Director Stahlman - Olaf Pooley
- Sir Keith Gold — Christopher Benjamin
- Petra Williams / Dr Williams - Sheila Dunn
- Greg Sutton / Greg Sutton (Inferno) - Derek Newark
- Private Latimer - David Simeon
- Private Wyatt - Derek Ware
- Harry Slocum - Walter Randall
- Bromley/loudspeaker voice (uncredited) - Ian Fairbairn
- RSF Sentry - Roy Scammell
- Patterson - Keith James
- Primords - Dave Carter, Pat Gorman, Walter Henry, Philip Ryan, Peter Thompson
- Writer - Don Houghton
- Action / Stuntwork - HAVOC
- Assistant Floor Manager - Sue Hedden
- Costumes - Christine Rawlins
- Designer - Jeremy Davies
- Film Cameraman - Fred Hamilton
- Film Editor - Martyn Day
- Make-Up - Marion Richards
- Production Assistant - Chris D'Oyly-John
- Script Editor - Terrance Dicks
- Special Sounds - Brian Hodgson
- Studio Lighting - John Green
- Studio Sound - John Staple
- Theme Arrangement - Delia Derbyshire
- Title Music - Ron Grainer
- Visual Effects - Len Hutton
- Producer - Barry Letts
- Director - Douglas Camfield
- The Doctor claimed a dimensional paradox would result from bringing anyone from the Parallel Earth back to Earth's universe, although this was later disproven when survivors of the cataclysm managed to find a way to travel between dimensions and attempted to take the places of their parallel selves (PDA: The Face of the Enemy)
- The Doctor sarcastically wonders whether Sutton was expecting his TARDIS console to resemble a space rocket with Batman at the controls.
- The TARDIS console is removable and can travel by itself, although it needs an external power source to do this.
- This story had the working titles of The Mo-Hole Project, Operation: Mole-Bore, The Mole-Bore, Project Inferno.
- An episode of The Romans also bore the title Inferno.
- The primordial mutant creatures are named 'Primords' in the closing credits of the episodes in which they appear and in publicity material, but are unnamed in the story's dialogue.
- The opening credits for this serial were unusual in that after the initial titles, the name and part number of the serial were superimposed on footage of a lava flow, with no music.
- In spite of Douglas Camfield receiving sole credit as director, the second studio-recording block and studio blocks 3 & 4 were directed by producer Barry Letts after Camfield had a minor heart attack on 27th April 1970. Letts later stated that Camfield's preparations were so meticulous, that he just followed the other man's plans anyway. Camfield remained credited as director, as BBC regulations at the time forbade the same person being credited as producer and director.
- Derek Ware did not actually perform the scene where the mutated RSF Private Wyatt is shot and falls to his death from the top of one of the cooling towers, in case he was injured, as he was also needed for studio recording. His place was taken by Roy Scammell, who strangely also played the RSF sentry who fires the fatal shot. Ware also stated in an interview that Scammell had already signed the contract to do the fall before Ware had been cast as Wyatt.
- The role of Petra was given to Sheila Dunn after Kate O'Mara was not available to play the part. O'Mara would, years later, be cast as the Rani, a renegade Time Lord.
- The name of the area in which the Inferno Project is taking place is named as Eastchester only once in the story – and this is in the scene cut from the UK transmission of Episode 5 (see Home video and audio releases below).
- Episode 6 has a small damaged section on the tape, which the Doctor Who Restoration Team replaced by painstakingly recolouring the appropriate section of the existing black-and-white film prints.
- Caroline John enjoyed her role as Section Leader Elizabeth Shaw and says that it was fun playing 'baddie' Liz. She also says she hated doing the scenes when she was playing the 'goodie' version because it was boring compared to being an evil character. She was particularly upset though about the scene in which Shaw shoots 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.
- Nicholas Courtney has also said he enjoyed playing the parallel version of the Brigadier, insofar he called it his "favourite" in an interview with Doctor Who Magazine in 2009.
- During the scenes set on the parallel Earth, images (supposedly) of the UK's dictatorial leader are seen on posters. The image used is that of Visual Effects Designer Jack Kine, in homage to the 1954 BBC adaptation of Nineteen Eighty-Four where the face of Big Brother was Head of Television Design Roy Oxley (Kine had worked on the visual effects for that production).
- Inferno marks the first story in Doctor Who to be set in a parallel universe.
- In the parallel world, the name tag on Director Stahlman's uniform reads "Stahlmann", despite the credits to Episode 5 spelling his name as "Stahlman", like his non-fascist counterpart. It is unclear whether the name tag is in error or the credits are in error. Episode 6 credits also read 'Stahlman' as warp 1 Stahlman appeares. The warp 2 name badge still reads 'Stahlmann'.
- Derek Newark played Za in An Unearthly Child, the very first televised Doctor Who story.
- Christopher Benjamin reappears as Henry Gordon Jago in The Talons of Weng-Chiang and he appears in the new series The Unicorn and the Wasp.
- The Scenes on top of the Nuclear Reactor in Episode 2 were not easy for Jon Pertwee, He was afraid of Heights, It took him 15 minutes just to sum up the confidence to film the scene.
- In Episode 3, during the chase scene on Parallel Earth, Bessie's bumper gashed open stuntman Alan Chuntz's leg as it passed, The gash was so severe that he had to go to the A+E, Barry Letts stated on the DVD commentary that "It was the worst wound [he]'d ever seen" and after Pertwee saw the wound and learning he caused it, he became sick and almost couldn't carry on filming until a few hours later. Jon Pertwee even went as far as to buying Chuntz's wife a gift to apologize for the accident.
- The song the Doctor sings at the beginning of episode one is "La Donna È Mobile" from Verdi's Rigoletto, albeit with greatly altered lyrics. His eleventh incarnation sang the same song in The Lodger.
- Episode 1 - 5.7 million viewers
- Episode 2 - 5.9 million viewers
- Episode 3 - 4.8 million viewers
- Episode 4 - 6.0 million viewers
- Episode 5 - 5.4 million viewers
- Episode 6 - 5.7 million viewers
- Episode 7 - 5.5 million viewers
- The 'parallel universe' aspect of the story was added to the scripts at the production team's suggestion to ensure that there was sufficient material to fill seven episodes - this was referenced by Terrance Dicks on subsequent documentaries.
- This was Caroline John's last story as Liz as she was pregnant and could not return for the following season. (Although it is true that the actress was pregnant, Barry Letts was unaware of this when he decided against renewing her contract.)
- Kingsnorth Industrial Estate (formerly Berry Wiggins and Co Ltd), Hoo St Werburgh, Kent
- Ealing Television Film Studios, Ealing Green, Ealing
- BBC Television Centre, Shepherd's Bush, London
- On the Nuclear Output Gauge in the Doctor's workshop, Mega-volts is spelled 'Megga Volts'.
- In episode 6 the Doctor, Liz, Greg, Petra and the Brigade Leader ignore a fire extinguisher in the Brigade Leaders office at a time where they really need them.
- During some shots of episode 6 when Sutton is holding off the Primords with coolant none is coming out.
- In episode 7 the dead Primord Stahlman has a litle bit of human skin poking out of his neck.
- Professor Stahlman's white coat has the name Stahlmann when he is actually credited as Stahlman.
- NA: Timewyrm: Revelation states that the dictator was one of the alternative regenerations the Time Lords offered the Doctor in DW: The War Games.
- Liz Shaw does not feature in any subsequent serials, although an illusory image of her is seen in DW: The Five Doctors (and the character is one of many in DW: Dimensions in Time). The circumstances surrounding her departure from UNIT are told in the MA The Scales of Injustice. In the next serial, DW: Terror of the Autons it is merely mentioned that Liz went back to Cambridge.
- This story marks the last appearance of the original TARDIS console which had been used on the series since the very first story, DW: An Unearthly Child.
- PDA: The Face of the Enemy is a sequel to Inferno, revisiting the 'alternate' world.
- The Doctor also travels to a parallel universe where there is a Republic of Great Britain in the Tenth Doctor story DW: Rise of the Cybermen / The Age of Steel.
- The Doctor's remark that he had heard the screeching sound the Primords made before at Krakatoa could imply that he had encountered (or at least heard) the creatures before. In the 2005 series episode DW: Rose a sketch that washed up on the shores of Sumatra following the eruption was seen, depicting the Ninth Doctor in front of a volcano (the two versions might have been in separate areas, near the vicinity of Krakatoa). Also during the Krakatoa eruption, the Xylok which became Mr Smith was unearthed.
- The Welsh village of Cwmtaff started a great drilling project into the Earth's crust in the year 2020. (DW: The Hungry Earth)
- The Doctor would later sing "La donna è mobile," again with altered lyrics, while in the shower in DW: The Lodger.
Home video and audio releases
Released as Doctor Who: Inferno.
- Commentary by Nicholas Courtney, Barry Letts, Terrance Dicks and John Levene.
- Can You Hear the Earth Scream? - A 35-minute documentary that looks at the making of Inferno. With contributions from Caroline John, Nicholas Courtney, John Levene, Ian Fairbairn, Barry Letts, Terrance Dicks and Derek Ware.
- The UNIT Family (Part One) - A 36-minute documentary that looks at the role of UNIT in the world of Doctor Who through to the end of Jon Pertwee's first year as the Doctor.
- Deleted Scene - A 2-minute scene not included in the UK transmission of Episode 5 the story, but which was retained for overseas screening.
- Visual Effects Promo Film - An excerpt from a BBC Visual Effects Department showreel.
- The Pertwee Years - Introduction - Jon Pertwee's original introduction to the final episode of this story.
- Radio Times Billings - Articles and listings from Radio Times (DVD-ROM PC/Mac).
- Doctor Who Annual 1971 (DVD-ROM).
- Editing for DVD release completed by Doctor Who Restoration Team.
This was released as a double-cassette pack on VHS in the UK in episodic format in March 1994, including in Episode 5 the scene not shown on the original UK transmission (see DVD releases above).
Novelisation and its audiobook
- Main article: Inferno (novelisation)
Stories in/featuring alternate/parallel universes
- NA: Blood Heat
- PDA: The Face of the Enemy
- DW: Rise of the Cybermen/The Age of Steel
- BFDE: Project Infinity
- PDA: The Quantum Archangel
- EDA: The Domino Effect, Reckless Engineering, The Last Resort
- DW: Turn Left
- Inferno at the BBC's official site
- Inferno at Shannon Sullivan's A Brief History of Time (Travel)
- Inferno at The Locations Guide