- The Invisible Enemy
] [cite web
title= The Invisible Enemy
publisher = A Brief History of Time Travel
last = Sullivan
first = Shannon
date = 2007-08-07
accessdate = 2008-08-30]
*Working titles for this story included "The Enemy Within", "The Invader Within" and "The Invisible Invader".
*It was not decided until late in the production that K-9 was to be a new companion. The decision to use it in multiple serials was made partly to offset the expense that had gone into making the prop. [cite web|url=http://www.shannonsullivan.com/drwho/serials/4t.html|title=The Invisible Enemy|publisher=A Brief History of Time (Travel)|accessdate=2008-02-18]
*Another reason that K-9 was included was to bring the show back toward its roots as a child-friendly series. Producers worried that the show had become too dark and adult, and family-values critic
Mary Whitehousehad been publicly attacking the show on these points. Changes such as K-9 and a move toward lighter scripts satisfied her enough that she ceased her attacks.
*The sequence in which the miniaturized clones of Leela and the Doctor journey inside the Doctor's brain was partially inspired by the 1966 film "
Fantastic Voyage". [ [http://www.bbc.co.uk/doctorwho/classic/episodeguide/invisibleenemy/detail.shtml Doctor Who Classic Episode Guide - The Invisible Enemy] ]
title=Doctor Who and the Invisible Enemy
isbn=0 426 20054 3
date=29 March 1979
preceding=Doctor Who and the Hand of Fear
following=Doctor Who and the Robots of Death|A novelisation of this serial, written by
Terrance Dicks, was published by Target Booksin March 1979.
Broadcast, VHS and DVD release
Reviewing the serial for "
The Times" newspaper on the Monday following the second episode's transmission, critic Stanley Reynoldsgave the story a generally negative reception. He also pointed out that in ITVregions where the series was competing with " Man from Atlantis", it was now losing the ratings war.
"In the current story, "The Invisible Enemy", now halfway through its four-week run, a malignant virus has struck a space station," wrote Reynolds. "Some evil force is attempting to take the station, and undoubtedly the universe, over. When one is being 'taken over' those sort of lightning flashes like the advert for learning how to hypnotize, travel from the eyes of the villain to the one having the fluence put upon him. One then gets rather furry of face and hand, but the appeal of "Dr Who" has always been the monster and this time out the BBC seems to have lost its touch with monsters... Maybe the leggy Leela is there for the dad and more earthy 14-year-olds, rather like those appalling rhythmic girls who practise dancing each week on "
Top of the Pops". Of course the return of the Daleks is all "Dr Who" needs; what the "Top of the Pops" girls need is something else, but that is neither here nor there." [cite news|title=Dr Who - BBC1|first=Stanley|last=Reynolds|publisher= The Times|date= 1977-10-10|accessdate=2007-01-14|pages=10]
*The story was released on
VHSin September 2002
*The DVD was released on 16th June 2008 in a double pack with the spin off "
K-9 and Company" called K-9 Tales.
*BBCCDW|id=invisibleenemy|title=The Invisible Enemy
*Brief |id=4t | title=The Invisible Enemy
*Doctor Who RG | id=who_4t | title=The Invisible Enemy
*OG review | id=4t | title=The Invisible Enemy
*DWRG | id=invi | title=The Invisible Enemy
*DWRG | id=invinov | title=Doctor Who and the Invisible Enemy
* [http://www.personal.leeds.ac.uk/~ecl6nb/OnTarget/1979/invisibl/79invisi.htm On Target — "Doctor Who and the Invisible Enemy"]
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