Synopsis:
Locked in the oxygen supply store, Victoria screams as she sees foam pour from a vent in the wall - with tendrils of seaweed squirming within it...
The Doctor and Jamie rush to her aid. They manage to unlock the door and pull her from the room just as Robson, Van Lutyens and the Chief Engineer arrive. Robson accuses Victoria of emptying the oxygen tanks and refuses to heed her description of the creature she had seen, thinking it her imagination. The Doctor confirms that she was locked in, from the outside.
Van Lutyens points out that it was not oxygen filling the room when they arrived, but some other, possibly toxic, gas. The person Victoria claimed to have seen in the room - the tall thin man - must have opened the vent.
In the family quarters, Harris is visiting his wife and is concerned about her health. As she becomes agitated, he is unaware that a piece of seaweed on the patio outside is becoming animated as though responding to her state of mind, continuing to emanate foam. Harris decides to seek the Doctor's help as the ESGO medic is out on Rig D at present. After he returns to the control centre, Maggie opens the patio door and stares at the weed, a pounding heartbeat sound filling her head.
The gas flow pressure drops once again. The Doctor tells Robson and the others about the heartbeat sound he and Jamie had heard in the impeller room, and Van Lutyens reminds them that this is what the control rig had reported. Robson points out that beneath the impeller shaft is a huge gasometer which acts as an echo chamber, and this is why the same sound can be heard here at the compound and out at sea on the rigs. He blames a mechanical fault, but the Doctor claims the sound is organic in origin. He insists they shut down the flow to investigate thoroughly but Robson once again refuses. Van Lutyens warns that his stubbornness could result in a gas explosion.
Jamie and Victoria, meanwhile, are chatting to Price, who handles communications. He explains to them the process connecting the compound with the rigs, showing them an illuminated plan.
Harris arrives back from his quarters and seeks out the Doctor, telling him of Maggie's illness.
Robson reluctantly allows the Doctor to go back with him - reminding him that they are still his prisoners.
Maggie receives a pair of visitors - technicians from the control centre named Oak and Quill. The latter is the man whom Victoria saw tamper with the oxygen tanks. The shorter, portly, Mr Oak speaks for the pair, claiming they have come to inspect an issue in the kitchen.
Van Lutyens and the Chief decide that the latest blockage must involve the impeller itself. The gas flow is coming in from the rigs - but not transferring outwards to distribution centres beyond the compound.
They notify Robson, who orders only a release of gas to reduce the pressure build-up.
Oak and Quill are working in the kitchen. They have seaweed-like growths emerging from their collars and sleeves. They open the patio door and calmly observe the mass of foam and weed, which moves towards the house. They then go to Maggie's bedroom where she is sitting at her dressing table. Seeing them in the mirror, she demands to know what they are doing there.
They open their blackened lips and emit a toxic gas which overpowers her.
Out on the beach, the gas release seems to have solved the immediate crisis - but the impeller still needs to be inspected. Price then reports that he is unable to contact Rig C.
The Doctor arrives at the Harris home, along with his companions, and they immediately smell the toxic gas. They find Maggie unconscious and smash the window to let the fumes escape.
The impeller is almost at a standstill, and the Chief thinks that it may be jammed at the base. It then stops, and he hears the heartbeat sound coming from the shaft.
The Doctor is told by Harris that his wife reported being stung earlier that morning, after finding a piece of seaweed in a folder. Victoria then spots a piece on the floor and the Doctor warns against anyone touching it. He suggests to Harris that someone must have placed the seaweed in the folder, intending himself to be the victim.
Jamie cannot see the threat from seaweed, after all the beach by the pipeline was full of it - a thought which alarms the Doctor.
Unable to get Robson to listen to his advice, Van Lutyens tries to get the Chief on his side. He is loyal to Robson, however, having worked with him for many years. They do agree that the impeller intake is the only place where something could get into the system unnoticed by CCTV.
They both hear the heartbeat sound, and the unnerved Chief decides to approach Robson with Van Lutyens' ideas after all - no longer able to dismiss the sound as mechanical.
They fetch Robson from his cabin but argue over what to do next - until all hear the sound again.
Van Lutyens warns "It's down there, in the pipeline, in the darkness, waiting...".
Data:
Written by Victor Pemberton
Recorded: Saturday 2nd March 1968 - Lime Grove Studio D
First broadcast: 5.15pm, Saturday 23rd March 1968
Ratings: 7.9 million / AI 55
VFX: Peter Day
Designer: Peter Kindred
Director: Hugh David
Additional cast: John Gill (Mr Oak)
The original draft for this episode seems to suggest that Oak and Quill (then named Swan) come from outside the compound.
Maggie asks her husband to fetch the Doctor to help her when she falls ill - puzzling Harris as to how she knew about him.
When everyone later arrived at her home they believed her to be dead.
The cliff-hanger was different - with Van Lutyens accusing Robson of being a murderer when they lose contact with the rigs, and he still refuses to turn off the gas flow.
One new character was omitted altogether - the Piston Engineer. His dialogue was given to the Chief.
Derrick Sherwin subsequently rewrote several dialogue scenes, mainly those involving Van Lutyens arguing with Robson and the Chief.
Only a small amount of filming was required for this instalment. This included more VFX shots of the seaweed and foam in the patio area.
For the sequence where the excess gas was released and burnt off, a section of pipeline was set up and filmed at Denham Airfield. This took place on Monday 12th February whilst close-up shots of various characters in the helicopter's cockpit were being recorded for later instalments.
John Gill, who joined the cast from Episode 2 as Mr Oak, was an old friend of the director and had appeared in several of his productions.
Sherwin was rewriting the instalment up to the day before recording, including reworking the scenes between Harris and the Doctor and the introduction of the sinister technicians.
The attack on Maggie was originally scripted to be on film. Gill and Bill Burridge chewed charcoal biscuits just before recording, to blacken their mouth and lips. The camera zoomed in on their open mouths and the director cross-faded between them and Maggie - the sequence ending with a fade into the burning gas shot filmed at Denham.
Gill and Burridge also had latex fronds resembling seaweed attached to their arms.
Frazer Hines smashed a prop window with a chair, and the dialogue was amended on the day to make it clear that the toxic fumes were not the natural gas viewers would have in their home. It was also made clear that Maggie had survived the attack on her.
The opening credits began over a filmed reprise of the cliff-hanger to the previous week, whilst the closing credits rolled over a close-up of the impeller shaft window following Van Lutyens' ominous words.
Two of the episodes will end on pieces of dialogue rather than visual threats / incidents - pointing to the fact that Pemberton's script was geared more for radio, as Sherwin and David had complained.
When the censor clips were recovered from Australia towards the end of 1996, courtesy of fan Damian Shanahan, included were many scenes from episodes which no longer exist. All were welcomed, but one sequence in particular stood out amongst the drowning mad scientists, murderous pirates and rampaging Yeti.
It was the scene from this episode in which Mr Oak and Mr Quill attack Maggie Harris. It was there in the soundtrack and in the telesnaps, but no-one knew just how disturbingly creepy it looked. The fact that it's one of the longest censor clips shows just how frightening the Australian censors thought the whole thing.
It's partly the fact that the technicians remain silent and seemingly benign until they open their blackened lips and hiss out the toxic gas. Their comic appearance, based as they were on Laurel & Hardy, juxtaposes with the horrific nature of their attack - the victim an ordinary housewife sitting alone in her bedroom. The close-up on the cadaverous Mr Quill's face is particularly disturbing, and I'm sure viewers were freaked out by it at the time.
This will prove to be a rare example of an "Everybody Lives" story, but the audience weren't to know that on 23rd March 1968.
Interestingly, the fan produced publication An Adventure in Space and Time, which looked at each story of the 1960's in turn, does not single out this scene in its two page review (Issue 049). It does mention that victims of the weed can exhale toxic gas from their mouths - but not this sequence in particular. Considering that reviews were mainly written by people who recalled seeing the episodes on broadcast, it's surprising that it didn't stand out in the memory more.
Apart from this sequence, it continues to be a slow build, relying on atmosphere and developing the mystery. Other than the wriggling seaweed there's still no real hint as to the nature of the threat (the expected monster). Perhaps there are too many scenes of men arguing in rooms about the same thing over and over again at present, even if they are well acted - another pointer to Pemberton's background in radio drama.
- The ratings begin their slide this week, though the appreciation figure remains constant.
- Competition on ITV was very mixed, with different shows in just about every region. These included cartoons and several reruns of old adventure serials, some dating back to the 1950's.
- John Gill appeared in the 1963 film This Sporting Life - which also had in its cast William Hartnell, giving a performance which would help win him the role of the Doctor.
- Later in life Gill worked with director Roman Polanski, appearing in both Tess and Pirates.
- Radio Times published a small photograph of guest artist Victor Maddern, as Robson, to accompany the listing for this episode:





































