The Invisible Enemy (TV story)

Synopsis
A rocket with three men are near complete their mission to Titan Base until a course change puts the rocket in the path of a strange cloud in space. By the time they have arrived, they have changed and serve a sentient virus which threatens the galaxy. When the TARDIS picks up an emergency message, it flies into the cloud, infecting the Doctor himself. To save himself and others, the Doctor must undertake a dangerous journey.

Plot
The TARDIS is infiltrated by the Swarm - a space-borne intelligence that wishes to spread itself across the universe - and the Doctor is infected by its nucleus. The ship then materialises on Titan, one of the moons of Saturn, where the human occupants of a refuelling station have also been taken over.

The Doctor eventually collapses as a result of his infection, but first manages to relay to Leela the coordinates of a local hospital asteroid. At the Bi-Al Foundation, based on the asteroid, Professor Marius clones the two time travellers, miniaturises the clones using the relative dimensional stabiliser from the TARDIS and then injects them into the Doctor's body in the hope that they can find and destroy the nucleus.

The plan backfires as the nucleus escapes from the Doctor in place of the clones and is enlarged to human size. The creature arranges for itself to be taken back to Titan, where breeding tanks have been prepared for it.

The Doctor, now cured of its influence, enlists the help of K9, Professor Marius's dog-shaped robot computer, and sets a booby-trap that results in the breeding tanks being blown up, killing the nucleus. Marius gives K9 to the Doctor as a parting gift.

Cast

 * The Doctor - Tom Baker
 * Leela - Louise Jameson
 * Voice of K9 - John Leeson
 * Lowe - Michael Sheard
 * Safran - Brian Grellis
 * Meeker - Edmund Pegge
 * Silvey - Jay Neill
 * Crewman - Anthony Rowlands
 * Nucleus - John Scott Martin
 * Nucleus Voice - John Leeson
 * Professor Marius - Frederick Jaeger
 * Parsons - Roy Herrick
 * Cruikshank - Roderick Smith
 * Marius' Nurse - Elizabeth Norman
 * Reception Nurse - Nell Curran
 * Opthalmologist - Jim McManus
 * Hedges - Kenneth Waller
 * Medic - Pat Gorman

Crew

 * Assistant Floor Manager - Tony Garrick, Christabel Albery
 * Costumes - Raymond Hughes
 * Designer - Barry Newbery
 * Film Cameraman - Nick Allder
 * Film Editor - Glenn Hyde
 * Incidental Music - Dudley Simpson
 * Make-Up - Maureen Winslade
 * Producer - Graham Williams
 * Production Assistant - Norman Stewart
 * Production Unit Manager - John Nathan-Turner
 * Script Editor - Robert Holmes
 * Special Sounds - Dick Mills
 * Studio Lighting - Brian Clemett
 * Studio Sound - Michael McCarthy
 * Theme Arrangement - Delia Derbyshire
 * Title Music - Ron Grainer
 * Visual Effects - Tony Harding, Ian Scoones

Biology

 * K9 states the first successful cloning experiments were carried out in the year 3922. He adds that "the Kilbracken holograph cloning technique replicates from a single cell a short lived copy. Efficiency of individualisation not completely guaranteed."
 * Professor Marius is said to be an expert in extra terrestrial pathological endomorphisms.

The Doctor

 * Leela tells the receptionist that the Doctor is from Gallifrey which she believes to be in Ireland.

Culture

 * Marius presumes that the Doctor is a spacenik.

TARDIS

 * The TARDIS' dimensional stabiliser just so happens to fit into Marius' equipment.
 * Leela seems to have learned how to operate the TARDIS since she is able to program it to go to the Bi-Al Foundation.

Theories and concepts

 * Leela's antibodies are a time paradox: 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 (as a result of her trip to 5000 AD!)

Story notes

 * This story had the working titles; The Invader Within, The Enemy Within and The Invisible Invader.
 * This story was listed on the 1970s sound effects LP as "The Enemy Within" which would go on to become the second-hand title given to the 1996 television movie.
 * This is the story which introduced K9.
 * This story also re-introduces the 'old' white console room (though slightly redesigned by Barry Newbery) rather than the 'wooden' secondary console room which debuted in The Masque of Mandragora.
 * 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.
 * This is the only story in which the monitor on K9's left side actually displays anything.

Ratings

 * Part 1 - 8.6 million viewers
 * Part 2 - 7.3 million viewers
 * Part 3 - 7.5 million viewers
 * Part 4 - 8.3 million viewers

Myths
to be added

Filming locations

 * Ealing Television Film Studios, Ealing Green, Ealing
 * Bray Studios, Slough
 * BBC Television Centre (Studio 6), Shepherd's Bush, London

Production errors

 * When the TARDIS first arrives on Titan, in the background you can see one of the relief ship crew still helmeted.
 * Marius' operating room is clearly a TV studio (it has no roof).
 * The first shot of the Bi-Al Foundation shows it with the damage later caused by the shuttle crash.
 * When K9 blasts a chunk out of the wall, it's obviously a pre-cut segment.
 * Lowe's "frozen" makeup changes between when he emerges from the freezer and when Leela brings him a cup of coffee.
 * The knife that Leela kills Meeker with is very obviously loosely sewn to his clothes. Notice how it wobbles back and forth after he falls.
 * In the very first scene, as the Doctor collapses to the ground, a person can be seen moving in the back of the set.
 * 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.
 * The countdown clock in Marius's lab speeds up and slows down as needed for the plot.
 * When the Doctor is congratulating himself on blowing up the Swarm, the shadow of a boom mike can be seen.

Continuity

 * K9 joins the Doctor and Leela, he departs with Leela in DW: The Invasion of Time.

Timeline

 * This story occurs after DWA: The Crocodiles from the Mist
 * This story occurs before VD: Crimson Dawn

DVD releases

 * Region 2 16th June 2008
 * PAL -


 * Region 4 4th September 2008
 * PAL -


 * Region 1 2nd September 2008
 * NTSC -


 * This story was on DVD release on 16 June, 2008 in a K9 Tales Box Set. It was released in the Box Set alongside K9 and Company.


 * Early versions of the box set feature a fault on The Invisible Enemy disc. A scene from half way through episode 3 is skipped and appears after the closing credits. 2 entertain is aware of the problem but have decided to go on with the release as planned. Though they are trying to fix the problem for later copies of the DVD box set.

Notes:
 * Editing for DVD release completed by Doctor Who Restoration Team.

K9 Tales
This story and K9 & Company were released as a DVD box set in 2008.

Novelisation and its audiobook

 * Main article: Doctor Who and the Invisible Enemy


 * Novelised as Doctor Who and the Invisible Enemy in 1979 by Terrance Dicks.