The Invisible Enemy (TV story)

The age of Man is over, Doctor. The age of the virus has begunNucleus

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

Crew

References

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.
Leela seems to have learned how to operate the TARDIS since she is able to program it to the Bi-Al.
Leela tells the receptionist that the Doctor is from Gallifrey which she believes to be in Ireland.
Marius presumes that the Doctor is a spacenik.

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 K-9.
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.

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

Discontinuity, Plot Holes, Errors

When the TARDIS first arrives on Titan, in the background you can see one of the relief ship crew still helmeted.
The cloning of the Doctor and Leela seems to have also cloned their clothes. No doubt due to 51st century technological advances in the field of not showing nudity on television.
The nucleus was clearly on wheels.
Several times during the episode, the signs for the "Isolation Ward" are spelled "Isolayshun."

Continuity

K-9 joins the Doctor and Leela, he departs with Leela in DW: The Invasion of Time.
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.

DVD, Video and Other Releases

DVD release

Region 2 16th June 2008

PAL -

Region 4 4th September 2008