4F. Terror Of The Zygons

Season Thirteen - 1975/1976

Script Editor: Robert Holmes
Writer: Robert Banks Stewart
Produced by: Philip Hinchcliffe
Director: Douglas Camfield
Designer: Nigel Curzon
Incidental Music: Geoffrey Burgon
Munro: Hugh Martin (1)


In the North Sea, off the coast of Scotland, a radio operator on board an oil rig hears a strange sound moments before the oil rig is attacked and destroyed.

After receiving a call from the Brigadier the TARDIS materialises in a forest. The Doctor, Sarah and Harry emerge from a invisible TARDIS. The Doctor assures them they are on Earth, and whilst he goes back inside the TARDIS to make it visible Harry tells Sarah he fully expects to see a herd of Jabberwockys coming towards them. When the Doctor emerges from the TARDIS he is wearing a Balmoral on his head, and tells Sarah and Harry they have materialised in Scotland. The Doctor also has a device than can track UNIT's signal, and after a short trek across the countryside they see the Brigadier's car travelling into a small village. They manage to catch a lift from the Duke of Forgill, a local landowner who owns most of the area, to a hotel.

In the hotel the Brigadier, dressed in the Stewart tartan, is trying to have a talk with Mr Huckle about the missing oil rigs, but the landlord hotel's persistent bagpipe playing is distracting. The Doctor, Sarah and Harry arrive just as the meeting finishes. The Duke of Forgill and Huckle do not get along, and Forgill warns Huckle not to let his men poach on Forgill's land, or they will be shot.

The Doctor wants to know why the Brigadier has called him back to Earth, and the Brigadier explains that three oil rigs have disappeared. The Brigadier takes the Doctor, Sarah and Harry to see Huckle at the oil company. Harry takes a look into the injuries and deaths of the oil workers whilst Sarah goes back to the village to ask the locals about the incidents. The Doctor is more curious about the supposedly unsinkable oil rigs.

Back at the hotel, the Fox Inn, Sarah talks to  the landlord, Angus Ferguson McRannald. As the seventh son of a seventh son there are rumours that McRannald has a 'second sight'. Sarah admires a deer's head mounted on a wall, shot by Forgill, head or the McRannald clan. Sarah said Forgill seems odd, and McRannald says he had not been the same since the oil companies came.

McRannald also tells Sarah about disappearances that have occurred on Tulloch Moor, going as far back as 1870. When mist came down two brothers were caught. One was killed, and other lost his mind and never spoke again.

Harry, returning from the sick bay at the oil company, sees a man staggering around near some sand dunes collapse. It is the radio operator from the oil rig. He starts to explain what happened but is shot by 'the Caber'. As Harry tries to see who the shiper is he is also shot. Harry has a scalp wound and is taken to the oil company sick bay. As the Doctor and Sarah visit Harry the Brigadier tells them another rig has been destroyed.  Sarah stays with Harry as the Doctor, the Brigadier and Benton return to the inn.

Earlier in the day the Brigadier had been examining wreckage of the previous oil rig, and in the back of Benton's Jeep is a piece of wreckage with curious markings. The Doctor takes a cast of the damage and the result is what looks like a large animal's tooth.

In the sick bay when Harry starts to recover Sarah telephones the inn to let the Doctor know, and is attacked by a Zygon. Hearing the scream through the telephone the Doctor and Benton set off for the sick bay. Once there Sister Lamont tells them Harry and Sarah have disappeared, although Harry's room's window is open. Whilst Benton organises a search of the moors Lamont and the Doctor split up to search the sickbay. The Doctor examines a room that houses equipment for their divers. Inside a decompression chamber the Doctor finds Sarah. As he goes inside the door is closed by a Zygon and it starts decompression. As Sarah struggles to breathe the Doctor hypnotises her and once she is in a trance the Doctor tells her she does not need to breathe.

Meanwhile Harry is taken inside the Zygon ship and introduced to Broton, Warlord of the Zygons, who says Harry could be useful to them. Broton tells Harry that the Zygon ship landed centuries ago and was waiting to be rescued. After hearing of their planet's destruction they have decided to take over Earth. Harry is then taken away to a room where his body print will be copied allowing the Zygons to make copies of him. In the room he can already see humans that have already been copied, including Sister Lamont and the Caber.

At the inn the Brigadier is coordinating a search of the coastline when a corporal notices smoke. The Brigadier, the corporal and another soldier are overcome by the fumes.

At the sickbay Benton sees the decompression chamber and stops the decompression. Inside he finds Sarah still in a trance and the Doctor okay after putting into practice a trick he learnt from a Tibetan  monk. They get back to the village to find everyone in the village is unconscious after having being gassed. In the Zygon ship Broton is not happy when hears the Doctor and Sarah are still alive. Through cameras hidden in the inn Broton is able to watch the Doctor as Huckle arrives to show his a strange object that was found in wreckage, a signal device (trilanic activator) for the Skarasen who have been chewing up the oil rigs.

When a solider is killed on the moors Benton calla for the Doctor and the Brigadier, leaving Sarah alone in the inn in case Harry returns. Harry does return and picks up the device, saying the Doctor asked him to collect it. As he runs off Sareah follows him through the village. Hearing a noise in a barn Sarah investigates and is attacked by Harry. She moves out of the way and Harry falls onto machinery. When Sarah looks she sees a Zygon as it dies.

In the ship, once the Zygon has dies, Harry recovers and frees himself. In the control room Zygons detect Harry's awakening and test the synchron response with the Zygon, Madlar, and find there isn't one any more. They immediately activate molecular dispersal, and in the barn the Zygon disappears.

At the inn Sarah suggests that they are being watched, and the Brigadier orders Benton to search the inn for bugs. Realising this Broton orders a Zygon to send the Skarasen to attack. In the inn the signal device starts signalling. The Doctor takes the device onto the moors to lead the Skarasen away from the village to give the Brigadier chance to find the source of the signal, which turns out to be Loch Ness, making the Skarasen the Loch Ness Monster.

On the moors the Skarasen stands on the device and it stops signalling. Thinking the Doctor is dead the Zygons recall the Skarasen. The Doctor is met on the moors by Sarah and the Brugadier, and together they visit the Duke at Forgill Castle. The Brigadier wants to drop depth charges in Loch Ness, and asks for Forgill's permission as he owns part of the shoreline. Forgill is reluctant to give the permission. Forgill doubts the 'Loch Ness Monster' travels overland from Loch Ness to the North Sea, and the Doctor tells him that there is a subterranean channel that the monster can use, and that it is actually a cyborg being controlled by aliens. The Doctor surmises that in the past the Skarasen has been able to come and go as it pleases, but now that the oil companies have set up in the area that has been made more difficult.

At the inn McRannald is continuing the search for cameras, and thinks there is one in a deer's head given to the inn by Forgill. As he is checking Sister Lamont enters the inn and transforms into a Zygon. McRannald cries out, and outside Benton and other UNIT soliders hear him. Inside they find only his body and immediately start a search off the forest for the killer. When they see a Zgyon they start shooting, and Benton otrders a soldier to tell the Brigadier they have found one.

At the Castle the Brigadier receives the call, and he and the Doctor go to the forest leaving Sarah to find out more information about the area. The Brigadier meets Benton back at the inn where Benton tells him that the Zygon turned back into Lamont and drove off. The Doctor sees that the deer head no longer has any eyes, and realises that this is where the camera was. The head was given by Forgill meaning he knew about the camera, and could be a Zygon, and they left Sarah at his castle.

At the Castle Forgill leaves Sarah alone to look at books and records he has. One of the books opens a hidden door to a passage that leads down into the Zygon ship. In the ship Sarah finds the duplication room, and finds Harry in a cell. They make it out of the ship and back to the Castle where they find the Doctor and the Brigadier. The Doctor immediately goes down passage into the ship. When the hear him scream the Brigadier, Sarah and Harry set off after him, but are stopped by Zygons, who disappear back into the ship closing the passage.

The Brigadier takes some troops to the shore of the loch and start firing mortars. Even though the ship was already crippled it is capable of limited flight, and after the first couple of mortars Broton orders a Zygon to fly the ship away from the Loch. The Brigadier calls UNIT HQ to track the ship, but they loose the ship as it jams all the radar. The Skarasen is left to follow by itself in the sea.

Sarah and UNIT return to UNIT HQ in London still not knowing where the ship is. For the ship to remain hidden Broton has ordered that no external communication is allowed, and that internal communications should be on half power. In a cell the Doctor tests how poweful half power is by touching two live wires, short-circuiting the communications and sending out a signal that Benton at UNIT HQ can trace to a disused quarry near Brentford.

Broton and another Zygon try to stop the Doctor. When they reach his cell they find him collapsed on the floor. Thinking he is dead they leave him, and Broton, disguised as Forgill, starts phase two of the plan by setting the Skarasen activator signal at its next target. After Broton leves the Doctor is able to free the real Forgill, Lamont and Caber from the duplication room, lure the Zygons out of the control room and lock themselves inside. The Doctor sets the ship's self destruct. UNIT arrives at the quarry in time to see the Doctor, Forgill, Lamont and Caber escape as the ship blows up.

Most of the Zygons have perished, but Broton is still free. Forgill tells the Doctor that the Fourth International Energy Conference at Stanbridge House is about to take place - on the edge of the Thames. The Duke is the President of the Scottish Energy Commission, so Broton will easily be able to get through the security.

They return to Stanford House and find Broton in the basement in Zygon form. The Brigadier and UNIT open fire and shoot Broton. As he dies Broton tells them the Skarasen will destroy them all. The Doctor realises Broton has put the signalling device in his pocket, and he rushes to a balcony and throws the device to the Skarasen. Once the Skarasen has finished eating the device it returns home - to Loch Ness.

The Doctor, Sarah and Harry return to Scotland to find the TARDIS. Sarah decides to keep travelling with the Doctr, but Harry decides that staying on Earth is better for him.

Regular Cast

  • Sarah Jane Smith: Elisabeth Sladen
  • Harry Sullivan: Ian Marter
  • Brigadier Lethbridge-Stewart: Nicholas Courtney
  • RSM Benton: John Levene

Guest Cast

  • Duke of Forgill/Broton: John Woodnutt
  • Sister Lamont: Lillias Walker
  • The Caber: Robert Russell
  • Zygons: Keith Ashley, Ronald Gough (1-2)
  • Angus Ferguson McRannald: Angus Leanie (1-2)
  • Huckle: Tony Sibbald (1-2)
  • Radio Operator: Bruce Wightman (1)
  • Corporal: Bernard G. High (2)
  • Soldier: Peter Symmonds (2)
  • Soldiers: Alan Clements (4), Roland Geall, Patrick Ginter, James Muir (1-3), David Selby, Barry Summerford (2-4)
  • Additional Zygon voices: Robert Russell, Lillias Walker

Original broadcast on the BBC

Channel Title Date Viewers Rating
BBC 1 402. Part One Saturday, August 30, 1975 5:45 PM - 6:10 PM 8.4M 59%
BBC 1 403. Part Two Saturday, September 6, 1975 5:45 PM - 6:10 PM 6.1M
BBC 1 404. Part Three Saturday, September 13, 1975 5:45 PM - 6:10 PM 8.2M 54%
BBC 1 405. Part Four Saturday, September 20, 1975 5:20 PM - 5:45 PM 7.2M


  • Television Centre Studio 3
  • Television Centre Studio 4

Outside Locations

  • Ambersham Common, nr. Midhurst
  • Charlton, Sussex
  • Furnace Pond, Crabtree, nr. Lower Beeding
  • The Mill, Climping, nr. Littlehampton, Sussex


Part 2: When the Doctor and the Brigadier are examining the soldier who was crushed by the Skarasen, you can see one of the soldier's fingers move very slightly.

Part 3: When Sarah is wandering around the Zygon spaceship you can clearly see the outline of her undergarments through her clothes.

Part 3: n the scene where the duplicate Harry steals the transmitter from Sarah, the wound on his forehead is very light in colour (as if it had almost healed). When he runs out the door it is suddenly very dark red.

Working Titles

The Loch Ness Monster

The Loch Ness Terror

The Zygons


The bagpipes heard in the story were played by Angus Lennie, who played McRannald.

Ian Marter leaves at the end of the story, but returns for a guest appearance in The Android Invasion.