BBC Doctor Who - The Stories BBC
QuickNav to a Season: 
QuickNav to a Story: 
 
The Previous Story
The Invisible Enemy
 The Previous Story
The Previous Story
(Horror of Fang Rock)
 The Next Story
(Image of the Fendahl)
Season
Details
SynopsisGeneral
Information
The
Episodes
Audience
Appreciation
ArchivesNotesFirst and LastThe PlotQuote of
the Story
Release
Information
In PrintPhoto
Gallery
 

Tom Baker
The Invisible Enemy
Fourth Doctor Logo


Synopsis


K9
K9
 A three-man shuttle crew are completing the final stages of their journey to Titan base, when a course deviation puts the shuttle in the path of a mysterious cloud in space. The crew members arrive on Titan, but they have been somehow changed, infected by an intelligent virus that threatens everyone in the galaxy…

 The TARDIS picks up a Mayday message from Titan base, but before The Doctor and Leela can fully respond, the police box also passes through the mysterious cloud…

 With the infection spreading from person to person, The Doctor and Leela seek assistance on a medical station in the asteroid belt. As the situation worsens, their only hope lies in the unlikely combination of the eccentric scientist Professor Marius, and his dog-shaped computer K9…

Source: BBC VHS Video


General Information

Season: Fifteen
Production Code: 4T
Story Number: 93
Episode Numbers:458 - 461
Number of Episodes: 4
Percentage of Episodes Held:100%
Working Titles:"The Invader Within", "The Enemy Within" and "The Invisible Invader".
Production Dates: March - April 1977
Broadcast Started: 01 October 1977
Broadcast Finished: 22 October 1977
Colour Status: Colour
Studio: Bray Studios, Slough and BBC Television Centre (TC6)
Location: None
Writers:Bob Baker and Dave Martin
Director:Derrick Goodwin
Producer:Graham Williams
Script Editor:Robert Holmes
Editor:Glenn Hyde
Production Assistant:Norman Stewart
Production Unit Manager:John Nathan-Turner
Assistant Floor Managers:Christabel Albery and Tony Garrick
Designer:Barry Newbery
Costume Designer:Raymond Hughes
Make-Up Designer:Maureen Winslade
Cameraman:Nick Allder
Incidental Music:Dudley Simpson
Special Sounds (SFX Editor):Dick Mills
Studio Sounds:Michael McCarthy
Lighting:Brian Clemett
Visual Effects:Ian Scoones and Tony Harding
Title Sequence:Bernard Lodge
Title Music:Ron Grainer and the BBC Radiophonic Workshop. Arranged by Delia Derbyshire
Number of Doctors: 1
The Doctor: Tom Baker (The Fourth Doctor)
Number of Companions: 2The Companions: Louise Jameson (Leela) and John Leeson (voice only) (K9 Mk I) (Joins) Additional Cast: Frederick Jaeger (Professor Marius), Michael Sheard (Lowe), Brian Grellis (Safran), Edmund Pegge (Meeker), Jay Neill (Silvey), Anthony Rowlands (Crewman), John Leeson (Nucleus Voice), Roy Herrick (Parsons), Elizabeth Norman (Marius' Nurse), Nell Curran (Reception Nurse), Jim McManus (Opthalmologist), Roderick Smith (Cruikshank), Kenneth Waller (Hedges), Pat Gorman (A Medic), John Scott-Martin (Nucleus)Setting: Bi-Al Foundation, Asteroid K4067 (5000), Inside The Doctor's body and Titan Base, Titan (5000) Villain: The Swarm

The Episodes

No. Episodes Broadcast
(UK)
Duration Viewers
(Millions)
In Archive
458Part 101 October 197723'09"8.6PAL 2" colour videotape
459Part 208 October 197725'13"7.3PAL 2" colour videotape
460Part 315 October 197723'28"7.5PAL 2" colour videotape
461Part 422 October 197721'22"8.3PAL 2" colour videotape

Total Duration 1 Hour 33 Minutes


Audience Appreciation

Average Viewers (Millions) 7.9
Doctor Who Magazine Poll (1998)58.60%  (Position = 125 out of 159)
Doctor Who Magazine Poll (2009)58.10% Lower (Position = 164 out of 200)
Doctor Who Magazine Poll (2014)60.49% Higher (Position = 196 out of 241)


Archives


 All four episodes exist as PAL 2" colour videotapes.



Return to the top of this page
 


Notes


This story is considered by many fans of the show to be rather lacklustre. It is though, significant in the history of the shows for introducing K9, the robot dog voiced by John Leeson. Designed by Tony Harding, and built by the BBC Visual Effects department, K9 would become one of the show’s most popular elements.

Although this story was intended to be the second story broadcast as part of Season Fifteen it was recorded first. This was to allow time for the preceding story, "Horror of Fang Rock", to be written when it was decided, at short notice, to cancel a vampire-based story called "The Vampire Mutation" due to a fear that it could detract from the BBC’s high-profile adaptation of Bram Stoker's classic novel "Count Dracula", which was due for transmission close to when the story would have aired. Having been filmed first in the season this story was actually the first to be produced by Graham Williams.

This story was directed by Derrick Goodwin, whose career in television had largely centred on comedy shows (such as On the Buses and Thick as Thieves), although he had also worked on an episode of Z Cars. Derrick Goodwin later had to decline, due to scheduling conflicts, an invitation from Graham Williams to return to Doctor Who. So as well as being his first Doctor Who story it also turned out to be his only work on the show.

The voice of K9 was provided by John Leeson, who had appeared in comedy and children’s programmes, including Dad’s Army and Rainbow as well as being a BBC continuity announcer. The director for this story, Derrick Goodwin, had recently renewed the acquaintance of John Leeson, who he had first met while working in repertory theatre. John Leeson was originally contracted to voice K9 for the final three episodes of this story but his contract was extended to include the Voice of the Nucleus as well. In the closing credits for episodes Two to Four, John Leeson was therefore credited as ‘Nucleus and K9 Voice’.

It was not decided until late in the production that K9 was to be a new companion. The script for this story however, had been structured so that the scene in which K9 departs with The Doctor and Leela could simply be dropped if the character was not to be retained, leaving the implication that he had simply been returned to Professor Marius off-screen. Soon after recording of this story had been completed Producer Graham Williams decided to keep K9 on for at least the remainder of Season Fifteen despite the problems that the prop had posed.

Unfortunately the K9 prop quickly proved itself to be a source of frustration when it was discovered that the remote control mechanism sometimes interfered with the cameras, resulting in visual distortion on the recordings and the prop itself going haywire. Consequently, Tom Baker quickly grew frustrated with K9, occasionally going so far as to give the prop a solid kick. It has also been commented that Tom Baker also disliked the fact that the robot dog’s short stature meant that he often had to stoop down so that they could be in the same shot together. Fortunately, however, Tom Baker and John Leeson quickly developed a strong camaraderie. As K9 was now due to stay on in the show Tony Harding started formulating plans to overhaul the robot dog’s inner workings to make the prop more controllable and to prevent it disrupting the cameras.

With K9 continuing beyond this story John Leeson therefore became a member of the regular cast, as the voice of K9, which he would do for three of the four forthcoming seasons. The decision to use K9 in multiple stories was made partly to offset the expense that had gone into making the prop. Because of this the following stories in Season Fifteen had to be slightly rewritten to explain K9’s lack of involvement.

Michael Sheard, who played the part of Lowe, makes his fourth of six appearances in Doctor Who, his best known roles being Laurence Scarman in the 1975 story "Pyramids of Mars" and the Headmaster of Coal Hill School in the 1988 Seventh Doctor story "Remembrance of the Daleks".

Frederick Jaeger, who played the part of Marius, also played Jano in the 1966 First Doctor story "The Savages" and Professor Sorenson in the 1975 story "Planet of Evil".

Also amongst Derrick Goodwin’s cast was his wife, Elizabeth Norman, playing Professor Marius’ nurse.

This story saw a return to the original-style TARDIS Console Room, which was abandoned after "Pyramids of Mars", when the ‘wooden’ secondary Console Room, which had been introduced in the previous season’s story "Masque of Mandragora". The wooden version had warped while in storage, during the break between seasons, to the point that it was no longer usable. Producer Graham Williams therefore opted to return to a simplified variation on the predominantly white, more futuristic set employed during the shows’ first thirteen seasons. Longtime Doctor Who designer Barry Newbury elected to simply retain the traditional white TARDIS console prop which had been used prior to Season Fourteen. This version of the TARDIS Console Room would be used up until the 1983 Fifth Doctor story "The King's Demons".

Originally this story was to have featured the Key to Time, but subsequent stories could not be reworked at a late date so this particular storyline was postponed a year when it became the main theme for Season Sixteen.

The sequence in which the miniaturised clones of The Doctor and Leela journey inside The Doctor’s brain was partially inspired by the 1966 film Fantastic Voyage.

This is not the first story involving shrinking. Others include: the 1964 First Doctor story "Planet of Giants", the 1973 Third Doctor story "Carnival of Monsters" and the 1979 Fourth Doctor story "The Armageddon Factor". Also Virgin Books’ The New Adventures novel "Timewyrm: Revelation", written by Paul Cornell, involved a journey into The Doctor’s mind.

Attacked by the alien virus, The Doctor is seen lapsing into his first self-induced cataleptic trance since the 1979 story "The Brain of Morbius". His lack of consciousness was due to the Virus feeding on ‘intellectual activity’. Professor Marius is also heard to state that The Doctor has ‘a symbiotic self renewing cell structure’.

The use of Leela’s antibodies actually causes a time paradox as she is descended from people who left Earth after this story, and by being present in 5000 AD she gives humanity the antibodies she has always possessed.

Listen out for the scene in the second episode when Leela tells the receptionist that The Doctor is from Gallifrey which she believes to be in Ireland - much the same as Tegan Jovanka tells her captors in the 1983 Fifth Doctor story "Arc of Infinity". Gallifrey was also assumed to be in Ireland in the 1976 story "The Hand of Fear" and in the 2007 Tenth Doctor story "Human Nature/The Family of Blood" as well as in the Virgin Books’ The New Adventures novel "Blood Harvest" that was written by Terrance Dicks.

This story also reveals that Leela is left-handed, or at least writes with her left hand. Actress Louise Jameson is right-handed, but chose to make Leela a left-handed writer in order to increase her awkwardness at this task. Also, strangely, Leela seems to have learned how to operate the TARDIS since she is able to program it to the Bi-Al.

Professor Marius built K9 not only as a personal databank, but also to replace the dog he left behind on Earth. It is therefore strange that Professor Marius is content to part with his ‘best friend, as he is heard to say when referring to K9.

This is the only story in which the monitor on K9’s left side is seen to display anything.

K9 was originally to be called Pluto but this was changed to avoid the wrath of the Walt Disney Corporation who own the copyright for the name used for their famous cartoon dog.

It is not hard to miss the scene when K9 blasts a chunk out of a wall as it is obviously a pre-cut segment. Also when K9 shoots one of the infected men, the blast beam appears to come out of his eyes, then moves down to his snout as the camera moves.

Other apparent errors in this story include: when the TARDIS first arrives on Titan, in the background you can see one of the relief ship crew still helmeted, the first shot of the Bi-Al Foundation shows it with the damage later caused by the shuttle crash and strangely the countdown clock in Marius’s lab speeds up and slows down as needed for the plot.

The 51st century is a significant time in the Whoniverse. Aside from the Great Breakout mentioned in this story and being the home era of K9, the century will also bring a new ice age, a Sixth World War, time travel research leading to the Time Agency (all mentioned in the previous season’s story "The Talons of Weng-Chiang") and the time-portals in the ship where the events of the 2006 Tenth Doctor story "The Girl in the Fireplace" take place. The Doctor also states that this time period is when humans first travel outside the solar system, but that was later contradicted in the 2009 story "The Waters of Mars" when the Tenth Doctor implies it happens some time around 2089. Notable humans from the era include former Time Agent Captain Jack Harkness - who was a companion of the Ninth Doctor and the Tenth Doctor - and River Song.

This story was listed on a 1970’s sound effects LP as "The Enemy Within" which would go on to become an alternative title given to the 1996 television movie "Doctor Who: The Movie" that starred Paul McGann as the Eighth Doctor.

"The Invisible Enemy" was repeated on BBC One on consecutive Thursdays in July/August 1978.

This story was released on DVD as part of the "K9 Tales" box set along with the 1981 spin off-story "K9 and Company: A Girl's Best Friend". Editing for this DVD release was completed by the Doctor Who Restoration Team. Early versions of the box set feature a fault on "The Invisible Enemy" disc. A scene from half way through Part 3 is skipped and appears after the closing credits.

The Target novelisation of this story, written by Terrance Dicks and published in 1979, was planned to be re-released by Virgin Books’ in 1994 with cover art by Alister Pearson. This release however, was cancelled.



First and Last

The Firsts:

 The introduction of new companion K9 voiced by John Leeson.

 This first story to see the return to the original-style TARDIS console room, which was abandoned after "Pyramids of Mars".

 The first Doctor Who story to be directed by Derrick Goodwin.


The Lasts (Subject to Future Stories):

 The last Doctor Who story to be directed by Derrick Goodwin.


Return to the top of this page
 


The Plot

WARNING: May Contain SpoilersHide Text
Titan Base
Titan Base

While hovering in space around the year 5000 AD, the TARDIS enters a cloud of energy as is struck by lightning-like tendrils. The TARDIS has become infiltrated by the Swarm and as it spreads throughout the time machine’s systems it is able to enter The Doctor’s mind. He has been infected by the Nucleus, a space-borne intelligence which wishes to spread itself across the universe.

At first The Doctor does not seem to have been affected by the attack. And so on hearing a distress call The Doctor, along with Leela, decide to investigate. The distress call originates from Titan, one of the moons of Saturn, where, unbeknown by The Doctor, the human occupants of a refuelling station have also been taken over by the Nucleus.

The TARDIS materialises on Titan and as they start to search for whoever sent the distress signal and why. However, it is not long before The Doctor realises that he has become infected. The Doctor also realises that he has been chosen to be the host of the Nucleus of the Swarm, due to his incredible powers as a Time Lord.

Outside the TARDIS
Outside the TARDIS

As a result of the virus inside his body, The Doctor is eventually overcome and collapses. Leela it seems is unable to be infected and so the Nucleus declares her a reject and orders that she be killed. Luckily The Doctor manages to temporarily break free of his infection and as they re-enter the TARDIS he is able to relay to Leela the coordinates of a local hospital asteroid, the Bi-Al Foundation, before he collapses again. Accompanying them is Lowe who, unknown to The Doctor and Leela has also been infected by the Nucleus.

On arrival at the medical station, based on asteroid K4067, they meet Professor Marius who introduces the group to K9, his dog-shaped robot computer. Professor Marius then examines The Doctor and pronounces that there is little he can do. However, The Doctor devises a plan whereby if he clones himself and Leela and then miniaturises the clones, using the relative dimensional stabiliser from the TARDIS, they can then be injected by Professor Marius into his body, in the hope that they can find and destroy the Virus Nucleus. Once their task is completed the miniaturised clones, of The Doctor and Leela can then escape from The Doctor’s body through a tear duct.

The Doctor
The Doctor

Professor Marius agrees, even though the clones will only live for ten minutes due to problems with the cloning technique used, and so he injects the miniaturised clones, of The Doctor and Leela, into The Doctor’s neck. The miniaturised clones then spiral down into The Doctor’s bloodstream. In the meantime, while the sedated Doctor is in a medical room, Leela and K9 fight off the staff members of the hospital who have become infected by Lowe.

Inside The Doctor’s body the miniaturised clones, of The Doctor and Leela have a hazardous voyage through his body. But when they enter his mind they become separated. The Doctor’s clone however, eventually reaches the Nucleus. But he has no weapons with which to destroy the Nucleus. Worse still the Nucleus learns of the intended escape route out of The Doctor’s body as The Doctor thought of it. And so before The Doctor’s clone can stop it the Nucleus heads for The Doctor’s eyes.

And so when Professor Marius collects from The Doctor’s tear duct, what he believes to be the miniaturised clones of The Doctor and Leela and places them into the cloning booth, it is realised that The Doctor’s plan has backfired. As he operates the controls of the relative dimensional stabiliser to return them to normal size, he only becomes aware of the mistake when instead of having retrieved the miniaturised clones of The Doctor and Leela it is the prawn-like Nucleus that appears in the booth. Now enlarged to human size the creature arranges for itself, and the infected medical staff, to be taken back to Titan where breeding tanks have been prepared prior to its invasion of the galaxy.

Inside The Doctor
Inside The Doctor

With the Nucleus no longer in his body and with the remains of Leela’s clone, and so her immunity factor, introduced into his blood stream The Doctor realises he has been cured. With the infection still spreading throughout the Bi-Al Foundation The Doctor replicates an antidote and gives it to Professor Marius to use on the remaining medical staff.

The Doctor, Leela, and K9 then proceed back to the base on Titan in the TARDIS. There they just barely manage to fight off the infected humans. The Doctor though is able, with the help of K9, to set up a booby-trap by rigging up a blaster behind a door to fire into a cloud of Oxygen gas which is escaping from a tank. As intended, when the Swarm finally forces open the door, the blaster fires, igniting the Oxygen in Titan’s methane atmosphere destroying the Swarm and the base.

On returning to the Bi-Al Foundation Professor Marius gives K9 to The Doctor as a parting gift as the Professor has to return to Earth. The Doctor is at first reluctant, but Leela is delighted. In the end it is K9 who decides for himself, between staying with his creator or to accompany the time travellers, when he trundles through the open police box doors. Shortly after The Doctor and Leela follow him in the TARDIS dematerialises, leaving Professor Marius to reflect: ‘I only hope he’s TARDIS trained’.

 
Leela
Leela
The Doctor
The Doctor
The Doctor and Leela
The Doctor and Leela
Lowe
Lowe
 
Leela with Professor Marius and K9
Leela with Professor Marius and K9
The Nucleus
The Nucleus
The Nucleus of the Swarm
The Nucleus of the Swarm
K9
K9




Quote of the Story


 'It is the right of every creature across the universe to survive, multiply and perpetuate its species. How else does the predator exist? We are all predators, Doctor. We kill... we devour... to live. Survival is all... You agree?'

The Nucleus



Return to the top of this page
 


Release Information

FormatTitleRelease Date (UK)Code NumberCover ArtRemarks
Audio
LP
Science-Fiction Sound Effects No. 191978REC 316Sound Effects
Audio
Tape
Science-Fiction Sound Effects No. 191978Sound Effects
Video
VHS
The Tom Baker YearsSeptember 1992BBCV 4839PhotoClip only Introduced and commented on by Tom Baker Double cassette release
Audio
CD
30 Years at the Radiophonic Workshop1993BBC CD 871Photo-montageSound effects
Video
VHS
The Invisible EnemySeptember 2002BBCV 7267Photo-montage
Video
DVD
The Invisible EnemyJune 2008BBCDVD 1356Clayton HickmanPart of the "K9 Tales" box set along with spin off-story "K9 and Company"


In Print

FormatTitleRelease Date (UK)PublisherAuthorCover ArtRemarks
Novel
Novel
Doctor Who and the Invisible EnemyMarch 1978Target No. 36Terrance DicksRoy KnipeISBN: 0-426-20054-3
CD
CD
The Invisible EnemyAugust 2018Target No. 36Terrance DicksRoy KnipeAudio version of the Target Novel read by John Leeson (K9).
Doctor Who CMS Magazine (In Vision)Issue 25 (Released: July 1990)
Doctor Who Magazine - ArchiveIssue 134 (Released: March 1988)
Doctor Who Magazine - ArchiveIssue 271 (Released: November 1998)
Doctor Who Magazine - Time TeamIssue 355 (Released: April 2005)
Doctor Who Magazine - Time TeamIssue 357 (Released: June 2005)
Doctor Who Magazine - The Fact of FictionIssue 362 (Released: November 2005)
Doctor Who Magazine - ArticleIssue 510 (Released: April 2017)
Doctor Who DVD FilesVolume 133 (Released: February 2014)

Return to the top of this page
 


Photo Gallery


The Doctor and Companions

 
Tom Baker
The Fourth Doctor

   

Louise Jameson
Leela
 
John Leeson (voice only)
K9 Mk I
   




On Release

Audio LP - Sound Effects No. 19
Audio LP - Sound Effects No. 19

BBC
AUDIO
Tom Baker Years VHS Video Cover
Tom Baker Years VHS Video Cover

BBC
VIDEO
Sound Effects CD Cover
Sound Effects CD Cover

BBC
AUDIO
VHS Video Cover
VHS Video Cover

BBC
VIDEO
   
DVD Cover
DVD Cover

BBC
VIDEO



In Print

Target Book Cover
Target Book Cover

Target
NOVEL
 
Target Audio CD Cover
Target Audio CD Cover

BBC
CD
   


Magazines

Doctor Who CMS Magazine (In Vision): Issue 25
Doctor Who CMS Magazine (In Vision): Issue 25

CMS
Doctor Who Magazine - Archive: Issue 134
Doctor Who Magazine - Archive: Issue 134

Marvel Comics
Doctor Who Magazine - Archive: Issue 271
Doctor Who Magazine - Archive: Issue 271

Marvel Comics
Doctor Who Magazine - Time Team: Issue 355
Doctor Who Magazine - Time Team: Issue 355

Marvel Comics
   
Doctor Who Magazine - Time Team: Issue 357
Doctor Who Magazine - Time Team: Issue 357

Marvel Comics
Doctor Who Magazine - The Fact of Fiction: Issue 362
Doctor Who Magazine - The Fact of Fiction: Issue 362

Marvel Comics
Doctor Who Magazine - Article: Issue 510
Doctor Who Magazine - Article: Issue 510

Marvel Comics
Doctor Who DVD Files: Volume 133
Doctor Who DVD Files: Volume 133

GE Fabbri
   


Return to the top of this page
 
 
Who's Who
KJ Software
Who Me
Episodes of the
Fourth Doctor


Season 15 Press to go back to the previous visited page References
 
 
Doctor Who is the copyright of the British Broadcasting Corporation. No infringements intended. This site is not endorsed by the BBC or any representatives thereof.