The Invasion was the third story of season 6 of Doctor Who. It featured the Cybermen in what became their established form until Earthshock in 1982.
The Invasion also featured the second appearance of Alistair Gordon Lethbridge-Stewart, now promoted to the rank which became his best known title – Brigadier. It additionally introduced the organisation known as UNIT, as well as the character of Corporal (later Sergeant) John Benton. Behind the scenes, it was the start of Terrance Dicks’ record-setting tenure as script editor. Furthermore, it was the final major appearance of the Cybermen until Revenge of the Cybermen in 1975.
Episode 1 (Lost)
The TARDIS materializes in space over the dark side of Earth’s Moon, and is promptly fired upon by a missile from an unknown spaceship. The Doctor rushes to affect an emergency relocation out of the missile’s path. After rematerializing, the Doctor, Jamie and Zoe find they have arrived in the late 20th century just outside London. The TARDIS’ visual stabilizer circuit has become damaged, rendering the ship invisible.
In order to have the circuit repaired, they set out to find Professor Travers and ask for his assistance. A driver offers them a lift to London. A security guard on a motorbike follows in the distance. The driver alerts the travelers of the danger. They get clear of the area and hide in some bushes while the driver explains that passes are required to get in and out of International Electromatics. He himself got in alright, but getting out might just be a bit more difficult. He tells them of the company International Electromatics. The driver tells them that IE have set up factories and houses, all of the local people have been bought out, and most of them join the company, while others have vanished. Once the coast is clear, they return to the truck.
At the guard post, two security guards note the truck driving towards the entrance. The truck stops at the post and the driver shows the guard his pass. The guard looks at him and then hands it back to the driver. The truck continues, but once it is a couple of yards away, the driver soon realizes there is another problem. A motorbike stops at the guard post entrance. In the distance, the driver stops the truck, opens the back and the Doctor, Jamie and Zoe get out of it.
The security guards arrive on the scene, and one of them tells the driver that he will have to come back with them for questioning. The driver refuses to return to the compound with them, telling them there is nothing they can do to make him. The guards pull out their guns, there is a sudden gunshot, then a second one. The driver collapses. Once the third shot has been fired, there is a silence — the driver is dead.
Meanwhile, the Doctor and his companions get another lift from a car driver. When they arrive at the professor’s home, they find that he has left for America, leaving his home in the care of Isobel Watkins and her uncle, Professor Watkins. She explains that the professor has disappeared, after he worked on an invention for International Electromatics. The Doctor and Jamie go to IE’s head office in London to investigate. When the computerised receptionist won’t let them past, they seek out another point of entry. They fall unconscious after being gassed, and are taken by security chief Packer to see IE’s Managing Director, Tobias Vaughn. Vaughn apologizes for the rough treatment they have endured. He explains that Professor Watkins was engrossed in a delicate stage of his work, and agreed to remain on site. The Doctor’s suspicions are piqued. After they leave, Vaughn opens a hidden panel in the wall of his office, revealing an alien machine.
The Doctor and Jamie are abducted by two men, later revealed to be Corporal Benton and Tracy. They are taken to an EC-130H Hercules transporter plane, housing a complete operations room, where they are met by the Brigadier. He explains about UNIT, and the task force’s investigation of IE.
Concerned about the Doctor and Jamie’s failure to return, Zoe and Isobel leave for IE in search for them. They also encounter the receptionist, but, instead of seeking another method of entry like Jamie and the Doctor, Zoe destroys the computer by assigning it an insoluble equation in ALGOL, causing its circuits to overload. Vaughn is watching, and once again opens the hidden panel. A decidedly inhuman voice speaking through the machine tells him that the Doctor and Jamie have been recognized from Planet 14, and are a threat to their plans. Vaughn orders Zoe and Isobel brought to him. Isobel is used to make her uncle, who is being held captive, co-operate.
The Doctor and Jamie return to Travers’ house, to find a note from Zoe and Isobel, explaining their going to search for them. They return to IE, and find several packing cases being loaded onto a train. Part of a feather boa Isobel gave to Zoe is hanging out of one of the boxes, alerting the Doctor and Jamie to the fact that their friend is inside. But before they can rescue Zoe and Isobel, the Doctor and Jamie are again captured by Packer.
The Doctor and Jamie are taken to Vaughn, where the Doctor accuses him of kidnapping Zoe and Isobel, a claim Vaughn flatly denies. Vaughn invites the two companions to come to the company’s country compound, where the train will be arriving; it is here they meet Professor Watkins, who has been warned to not mention Zoe and Isobel’s whereabouts. He shows the Doctor his cerebration mentor, a teaching device that is capable of inducing emotional changes.
The Doctor queries Vaughn of the deep space communicator he noticed when he came into the compound; in return, Vaughn demands that the Doctor explain about the failed circuit, even threatening to hand Zoe to Packer if he doesn’t co-operate. They are taken away.
Jamie and the Doctor fool Packer and escape in the elevator. They jam the elevator between the 4th and 5th floors, and decide to leave through the elevator shaft. Packer tries to kill them by sending the elevator to the top, but they escape onto the roof.
The Doctor and Jamie escape onto a railway siding. Whilst in the crates, Jamie has a near encounter with an automated cocoon.
Episode 4 (Lost)
The Doctor and Jamie emerge from the crates, and overhear guards being ordered to take Zoe and Isobel to the tenth floor.
Vaughn confides in Packer that he intends to use the cerebration mentor to control the Cybermen once they have invaded Earth; he also intends to use the TARDIS as a “getaway car”, should he fail.
Vaughn broadcasts over the intercom system to the Doctor that he has ten minutes to surrender or Zoe will be harmed. Using a communicator given him by the Brigadier, the Doctor calls for assistance from UNIT, who assist in rescuing Zoe and Isobel from the room in which they are locked. Realizing how dangerous UNIT are to his plans, Vaughn exercises hypnotic control over Major General Rutlidge, and orders him to cease UNIT’s investigations.
The Doctor examines photographs of UFOs over the IE factory, and reasons that those ships are bringing cocoons to Earth. He, along with Jamie, sneak into the London IE warehouse, where they witness the emergence of a Cyberman from its cocoon.
After witnessing the reactivation of the Cyberman, the Doctor and Jamie sneak back out of the IE warehouse. They return to UNIT HQ and warn the Brigadier that a Cyberman army is invading Earth, and that they are hidden somewhere in London. However, Rutlidge has ordered the Brigadier to cease all investigations against IE. Lethbridge-Stewart intends to gain authority from Geneva, but requires proof to back his reasoning. Isobel offers her expertise as a photographer, but the Brigadier refuses.
Vaughn tests Watkins’ device on an awakened Cyberman; however, the alien is driven mad by the machine and escapes into the sewers. Vaughn reveals that in an hour’s time the Earth will come under the control of the Cybermen through a micromonolithic circuit built into every IE device; the Doctor discovers this same circuit when he opens up an IE radio, and sets about making a device to block thetelepathic signal.
Meanwhile, Isobel, Zoe and Jamie have ventured into the sewers to obtain proof of the Cybermen’s presence on Earth. There they find the body of a policeman, who had followed them into the sewers and was subsequently killed by the Cybermen. They then encounter the insane Cyberman, who begins menacingly approaching the intrepid trio.
Isobel, Zoe, and Jamie narrowly escape from the sewers, and several of the Cybermen are killed by UNIT troops. Isobel has managed to snap some photos of the Cyberman. The photos, however, prove to be worthless as they look too much like fakes.
Watkins perfects his machine and delivers it to Vaughn, but discovers that the Managing Director has been partially cyber-converted, which protects him from bullets. UNIT manage to free Watkins from IE, during which time the Doctor creates aneuristor, which neutralizes the Cybermens’ hypnotic signals. The Brigadier orders the troops to have one of these taped to the back of their necks.
At dawn, the signal is broadcast, causing people around the world to collapse unconscious. The Doctor’s polarizer has fallen off and he begins to blank out, leaving the Cybermen able to take over London.
The Doctor is given a new polariser, and he and UNIT assess the situation, knowing the spaceship that the transmissions are coming from is on the Moon. UNIT decides to use a Russian rocket to destroy the source of Vaughn’s signal, while using UK missiles to destroy the incoming Cyberfleet. The Doctor heads off to talk to Vaughn. Captain Turner is sent to Russia to organize the rocket, while the Brigadier goes to the Henlow Downs missile site.
The Doctor stays behind to try to persuade Vaughn one last time to help his people. The missiles are successfully launched, with help from Zoe, and the Cybermen blame Vaughn for the setback in their plans, announcing that they will use a megatron bomb to destroy life on Earth.
A furious Vaughn uses the cerebration mentor to destroy the machine in his office. The Doctor persuades Vaughn to now aid humanity instead of trying to defeat it, and they take a helicopter to the factory, where they use Watkins’ machine to battle the massed army of Cybermen; UNIT forces arrive later to assist. Vaughn is killed in the skirmish, but the homing signal is successfully shut down.
The megatron bomb is destroyed by a missile, while the rocket destroys the last Cyberman ship, consequently stopping the hypnotic signal. With the crisis now over, and the visual stabilizer circuits now repaired, the Doctor, Zoe and Jamie depart in the TARDIS.