Stories Television Doctor Who Season 15 Serial: 1 2 3 4 5 6 The Invisible Enemy 1 image Overview Episodes Characters How to Watch Reviews 11 Statistics Related Stories Quotes 2 Transcript Overview First aired Saturday, October 1, 1977 Production Code 4T Written by Bob Baker, Dave Martin Directed by Derrick Goodwin Runtime 100 minutes Story Type New TARDIS interior, New Companion Introduction Time Travel Future Tropes (Potential Spoilers!) Disease, Hospital, Miniaturisation Location (Potential Spoilers!) Bi-Al Foundation, Titan, Titan Base Synopsis A three-man rocket crew are nearly done with 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 arrive, they have come under the control of a sentient virus which threatens the galaxy. When the TARDIS picks up an emergency message, it flies into the cloud, infecting the Doctor. To save himself and others, he must undertake a dangerous journey. Watch Watched Favourite Favourited Add Review Edit Review Log a repeat Skip Skipped Unowned Owned Owned Save to my list Saved Edit date completed Custom Date Release Date Archive (no date) Save 4 Episodes Part One First aired Saturday, October 1, 1977 Runtime 25 minutes Written by Bob Baker Dave Martin Directed by Derrick Goodwin UK Viewers 8.6 million Synopsis Deep space, 5000AD. An Earth supply shuttle is infected by a strange sentient space-borne virus, which quickly spreads to the crew of the refuelling station on the moon Titan. Even worse, the Doctor himself falls victim. But why is Leela immune, and what is the virus's ultimate goal? Part Two First aired Saturday, October 8, 1977 Runtime 25 minutes Written by Bob Baker Dave Martin Directed by Derrick Goodwin UK Viewers 7.3 million Synopsis Leela and Lowe take the Doctor to the Bi-Al Foundation for help. But how can they cure an infection of the mind? Part Three First aired Saturday, October 15, 1977 Runtime 25 minutes Written by Bob Baker Dave Martin Directed by Derrick Goodwin UK Viewers 7.5 million Synopsis Miniaturised clones of the Doctor and Leela are injected into his brain. But they must now fight the virus on its own level. And its servants are closing in around them. Part Four First aired Saturday, October 22, 1977 Runtime 25 minutes Written by Bob Baker Dave Martin Directed by Derrick Goodwin UK Viewers 8.3 million Appreciation Index 60 Synopsis The Nucleus, now grown to human size, is determined to spawn and take over the Galaxy. Only the Doctor and Leela can stop it. Show All Episodes Characters Fourth Doctor Tom Baker Leela Louise Jameson The Nucleus of The Swarm First Appearance K9 Mark I John Leeson First Appearance Frederick Marius First Appearance Show All Characters (5) How to watch The Invisible Enemy: Watch on iPlayer Blu-Ray The Collection – Season 15 DVD K-9 Tales VHS The Invisible Enemy (VHS) Reviews Add Review Edit Review Sort: Default Date (Newest First) Date (Oldest First) Likes (High-Low) Likes (Low-High) Rating (High-Low) Rating (Low-High) Word count (High-Low) Word count (Low-High) Username (A-Z) Username (Z-A) Spoilers First Spoilers Last 11 reviews 21 June 2025 New· · 77 words Review by kawaii2234 Spoilers 1 This review contains spoilers! I think the shrimp virus thingy's lungs (or whatever the organelle equivalent is) were probably regretting the whole become-a-giant-and-need-way-more-oxygen plan by like minute 3 seeing as it couldn't even move by itself. K-9 my beloved welcome to the show!!! The inside of the doctor's mind is visually stunning and the crew did a wonderful job of the sets. Overall the plot of this serial is absolutely bonkers with so many bizarre turns it's engaging all the way through. kawaii2234 View profile Like Liked 1 8 May 2024 · 250 words Review by 15thDoctor Spoilers 4 This review contains spoilers! Baker and Martin’s script is great, they have always been good at strange and psychedelic sci-fi concepts. Unfortunately their (admittedly ambitious) work is let down by the direction. Derrick Goodwin, in his one and only story on the show, does not manage the difficult balance of comedy and action the script gives him. The pacing is totally off, with plenty of awkward pauses throughout the 4 episodes which rip any tension out of the performances and presentation. There are excellent model shots and of course the amazing creation of K-9 to distract you. The way he is written in as a regular character is clunky, but you’re happy to have him (I hope he gets less noisy though). Some of the humorous characters work - the receptionist woman in particular is inspired. Others don’t. K-9’s original owner is a bit on and off form, depending on the scene - his last words “I hope he is TARDIS trained” were definitely not good enough for the whole story to go out. Totally off putting makeup on middle aged men that look very uncomfortable in it makes for unintentionally pitiable villains. If these are bad then don’t get me started on “the nucleus”. The downsides are so unfortunate, because at the heart of this story are some great gags and an interesting concept - an infectious disease in space. I’d love to see this story re-done as a new production. Or even as a Big Finish drama. There’s so much to love 15thDoctor View profile Like Liked 4 3 July 2024 · 506 words Review by WhoPotterVian 3 The Invisible Enemy is a curious case. It introduced one of the show's most iconic companions in K9 (so iconic, in fact, that he was even included in the level pack for LEGO Dimensions seven years after his last appearance in the series) yet his introductory serial is very average. The story sees the Doctor and Leela arriving at Professor Marius's ship where a three-man crew are under the control of the sentient virus the Nucleus. The Doctor is also infected and must be cloned so they can be inserted inside his body in order to stop the infection. The special effects are usually not one of the selling points of a classic series serial because they are under a shoestring budget but even taking that into account, they are terrible here. The Nucleus looks unconvincing, like a massive prawn; this is probably the one serial you should avoid showing to any new viewers at any cost. When the special effects are bad, you need your story to help those watching to forget it. Sadly, whilst the story isn't terrible it's not that brilliant either; however it does do something interesting with clones of the Doctor and Leela inside the Doctor's brain and the special effects during this sequence are on the better side for a classic series serial. With an average serial and a terribly designed monster, thank God then that the acting is on point. I think The Invisible Enemy shows Tom Baker at his best; he is brilliant throughout especially during parts three and four and you cannot detect the awkward relationship offscreen between Tom Baker and Louise Jameson at all (they infamously didn't get on well behind the scenes because Tom Baker didn't like the idea of the Doctor travelling with a violent companion as he believed it to be against the Doctor's moral compass). I also liked Frederick Jaegar; it is a shame he didn't become a recurring character as he is an engaging one. The serial is also nicely paced at four parts. The Invisible Enemy as a story would never be able sustain any more than that; as a six parter it would have really dragged so four parts feels like its natural length and if it had a lesser number it would arguably have had a bigger impact on the narrative forcing it to be tighter and rushed to a conclusion (something that some had a problem with for some of the new series' series 7 episodes - personally didn't bother me but I can see their point in terms of The Power of Three). It feels like it needed the four parts; no more, no less. Overall, this is a very average classic series serial let down by a terrible monster design and a forgettable narrative. K9 deserved a better introduction than this but at least it feels like its the right length, featured great acting and a character in Professor Marius who really should have been a recurring one (a trend in the Tom Baker era). WhoPotterVian View profile Like Liked 3 12 January 2025 · 150 words Review by dema1020 1 This is just alright. I found the story very mediocre, even if the idea of the main obstacle our heroes face is in the form of a virus. It sounds like a more interesting idea than what production was able to execute. K9's introduction is fine but otherwise it is a very underwhelming experience, only halfway salvaged thanks to the charisma of Tom Baker and Louise Jameson. In spite of it kind of being boring, the Doctor and Leela are entertaining enough on their own that The Invisible Enemy is still very watchable, even if it is just as easy to forget. It's pretty interesting to learn that Baker and Jameson apparently didn't get along much on set. You really can't tell thanks to the professionalism of these actors. I found that aspect quite impressive overall because it does feel like those two have good chemistry together on screen. dema1020 View profile Like Liked 1 23 May 2024 · 223 words Review by uss-genderprise Spoilers 2 This review contains spoilers! What a fun episode! The beginning is a little slow but it quickly picks up the pace. We've had space viruses before, but never one quite like this. A small detail but one I appreciated nonetheless was the secretary not questioning the Doctor's name at all. As a nonbinary person with many nonbinary friends, many of whom use nouns as names, I like the idea of that becoming ordinary in the future. I already adore K9. I love how he and Leela immediately got along the moment they realised the other isn't a threat. They have a surprising amount of things in common. (And who would have expected the Doctor to have a dog leash in his pocket? I'd love to know the backstory for that!) I think my only gripe with this story is the repetition of Leela being immune because she's a "savage". She's not any less intelligent than the other humans simply because she wasn't taught all the things they were! It's also a return to the thing that annoyed me the most in the early Three and Jo era, where the Doctor looks down on his companion and doesn't seem to actually *like* her. I have gotten a bit of that vibe with Leela but have managed to ignore it so far. I hope this changes in future episodes. uss-genderprise View profile Like Liked 2 Show All Reviews (11) Open in new window Statistics AVG. Rating435 members 2.93 / 5 Member Statistics Watched 826 Favourited 23 Reviewed 11 Saved 4 Skipped 2 Related Stories Main Range • Episode 189 Revenge of the Swarm Rating: 2.79 Story Skipped Audio Drama Reviews(2) More Actions View Sets Close Related Sets Set of Stories: Big Finish Main Range Set of Stories: Big Finish Main Range 151-200 Set of Stories: Main Range: Seventh Doctor Add Review Edit Review Skip Skipped Unowned Owned Save to my list Saved DWM Brief Encounters Tautology Rating: 2.50 Story Skipped Short Story More Actions View Sets Close Related Sets Set of Stories: Brief Encounters (Doctor Who Magazine) Add Review Edit Review Skip Skipped Unowned Owned Save to my list Saved Other adaptations of this story: We define an adaptation as a recreation of a similar story but on a different medium or with different characters. Target Collection Doctor Who and the Invisible Enemy Rating: 3.39 Story Skipped Book Reviews(1) More Actions View Sets Close Related Sets Set of Stories: Target Collection Add Review Edit Review Skip Skipped Unowned Owned Save to my list Saved Quotes Add Quote Link to Quote Favourite DOCTOR: Sometimes my brilliance astonishes even me. — The Invisible Enemy Show All Quotes (2) Open in new window Transcript Needs checking Part One [Bridge] (A spaceship carefully navigates an extremely dense asteroid field, and comes safely through to the other side. On the bridge, two crewmen in spacesuits, but without helmets, are dozing whilst the third is at the controls on an upper level by the forward windows.) MEEKER: Going to manual.SILVEY: What for?MEEKER: Why not? If we're going to be slammed around, I'd sooner do it myself.SILVEY: It's still telling you what to do.MEEKER: Yes, but at least I'm doing it. (The ship jerks sideways.) Show Full Transcript Open in new window