Doctor Who (1963–1989)
3 user

The Invisible Enemy: Part Four 

In trying to retrieve the clones from inside the Doctor, the alien virus is brought from the microbial world into the macro-world, and it's ready to spawn.



(by), (by)

On Disc

at Amazon




Episode cast overview:
... Doctor Who
... Leela
... Professor Marius
... Lowe
Brian Grellis ... Safran
Jim McManus ... Opthalmologist
... Nucleus / K9 (voice)
... A Medic
... Nucleus (as John Scott-Martin)


In trying to retrieve the clones from inside the Doctor, the alien virus is brought from the microbial world into the macro-world, and it's ready to spawn.

Plot Summary | Add Synopsis


TV-G | See all certifications »




Release Date:

22 October 1977 (UK)  »

Company Credits

Show more on  »

Technical Specs


Sound Mix:


Aspect Ratio:

1.33 : 1
See  »

Did You Know?


The script was originally structured so that the scene in which K-9 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. See more »


Doctor Who: The virus has a perfect right to exist as a virus, not as a giant storm threatening the entire solar system. Everything has its place, otherwise the delicate balance of the whole cosmos is destroyed.
Leela: I still say we should blow it up.
See more »

Frequently Asked Questions

This FAQ is empty. Add the first question.

User Reviews

S15: The Invisible Enemy: Maybe there is a good idea in there, but it is hidden behind the bad ones and fairly laughable designs
18 September 2016 | by See all my reviews

An odd start to season 15. The Horror of Fang Rock had its weaknesses, but in many ways it felt like an old style serial (Doctor #2) crossed with the slightly Gothic horror content that the last few seasons occasionally produced. This serial starts interestingly enough, with the Doctor seized by some sort of force which appears to also be seizing humans to make them prepare for a wider outbreak. However from the very start the design and the detail kept me from getting into it. The most obvious example is the 'possessed' effects, which are just hairy hands and the type of eyebrows that men my age tend to get whether we are preparing for a nucleus or not. These look cheap and are endlessly silly.

On top of this the detail of the story is weak. It is a bit of a 'base under siege' affair in some ways but mostly it doesn't really work in the first half. In the second half it just gets daft. The Doctor's clone enters his own head – and not in a theoretical way which one could go with, but in a real 'Innerspace / Fantastic Voyage' way. This element is daft in the concept, and really doesn't work at all in the execution. The design standards don't help but it doesn't do much interesting in there – or at least not interesting enough to cover for the weaknesses. The nucleus itself is a sight to see – a mix of a prawn, a rat, and one of those inflatable dancing men you see outside North American car showrooms. It is hard to take serious, particularly as it is forcibly wheeled around the place. Speaking of which, K9 makes an appearance here, and as much nostalgic charm as he/it brings, it is hard not to notice the limitations of the character even in the first outing. I do look forward to seeing how they manage to find a use for him moving forward.

The cast are mixed. Baker and Jameson aren't as good as the last serial, which is mostly down to the weaker material. The supporting cast are a bit wooden and do not bring much to the table in their characters. The special effects have some okay model work in there, although some of it is pretty rough (the spaceship moving up and down to avoid asteroids for example). The general design is poor though – some ambition perhaps, but not able to pull it off. Thinking back to the design work on Planet of Evil just a season or so ago, it is disappointing – but then on the other hand, this is the late 70's so maybe I expect too much.

All told, a mostly flat serial. There are some nice ideas but none really come together, and instead it is the weak design and silliness that sticks in the mind.

1 of 1 people found this review helpful.  Was this review helpful to you? | Report this
Review this title | See all 3 user reviews »

Contribute to This Page

Stream Trending TV Series With Prime Video

Explore popular and recently added TV series available to stream with Prime Video.

Start your free trial