The Yeti Comes Alive
After Salamander, the evil dictator The Doctor and his companions encountered in the previous story ("The Enemy of the World"), is ejected from the TARDIS, while the doors were still open, the time travellers are left clinging onto the central console. Eventually Jamie McCrimmon manages to move himself to a position where he can reach and operate the door controls which then close. With The Doctor back in control of the TARDIS he materialises it in space. But to the horror of The Doctor and his companions Jamie and Victoria Waterfield, a strange web-like substance begins to cover the exterior. To free the TARDIS, The Doctor carries out an emergency dematerialisation which frees the time machine from the strange web and they arrive on a London Underground station called Covent Garden. Strangely there are no people about.
On investigation they find that the whole station is deserted and the entrance gates locked. The Doctor also discovers that there is no power in the railway lines and so it is safe for them to investigate in the tunnels. It is not long before they discover a cable running down the tunnel. The Doctor follows the cable to another station (Charing Cross) where they are connected to crates of explosives. The Doctor then watches from hiding as two Yeti appear and start to spray a web like substance over the crates.
Meanwhile back in the tunnels Jamie and Victoria have followed the cable in the other direction. They are soon discovered by a group of soldiers, who are laying the cable, and are taken to an Army underground base at Goodge Street, commanded by a Captain Knight. There they discover that the London Underground has been sealed off due to it being infiltrated by a strange web and large hairy creatures – which Jamie and Victoria recognise as being Yeti. When they discover that Captain Knight is about to blow up the tunnel, that they last saw The Doctor in, they are forced to tell him about The Doctor – but it is too late to stop the setting off of the explosives. However, to the relief of Jamie and Victoria the explosives do not go off. It seems that the explosion had been neutralised by the Yeti's web.
|Victoria's New Look
Jamie and Victoria then meet Professor Travers who they originally met in Tibet. They learn that the current crisis was precipitated when Professor Travers accidentally caused one of the Yeti, that had been kept in a museum, to be reactivated, opening the way for the Great Intelligence to make another invasion attempt.
With the report that the web is once more moving through the tunnels engulfing the whole of the Circle Line so entrapping central London - and, a patrol returning having failed to locate The Doctor, Jamie decides to accompany another soldier so as to find The Doctor. However, they are soon attacked by a group of Yeti.
|The TARDIS is Attacked
Back at the base, Victoria overhears Professor Travers’ daughter, Anne, speculating that The Doctor might be behind the Yeti emergency and so heads off alone to the tunnels to look for The Doctor herself. With the Yeti in control of the tunnels and the web spreading ever closing the Army underground base eventually becomes surrounded. Victoria though is able to find The Doctor along with a Colonel Lethbridge-Stewart who takes command of the base. Then, while The Doctor and Anne work on a way to control one of the Yeti spheres, and with everyone else occupied, Professor Travers is kidnapped by a Yeti.
After an attempt to reach the TARDIS fails, and another attempt to blow up the tunnels is thwarted again by the Yeti, The Doctor, with the help of Colonel Lethbridge-Stewart and Captain Knight, go above ground and attempt to obtain some electronic components from a nearby shop so that The Doctor can build a control box that can be used to control a Yeti. But they are soon attacked, by the Yeti and Captain Knight is killed.
With so many things going wrong The Doctor suspects that someone within the Army underground base is working against them - either voluntarily or because they are being controlled by the Great Intelligence. Then, as the group ponders what to do next, the Yeti burst into the Army underground base with Professor Travers, whose mind has been taken over by the Great Intelligence. Using Professor Travers the Great Intelligence informs them that it had brought The Doctor here so that his memories and knowledge can be drained. And that unless The Doctor surrenders himself his friends will be killed. To make sure of The Doctor's co-operation, Victoria is taken to the Great Intelligence's control centre at Piccadilly Circus.
|The Doctor and Jamie
The Doctor has little choice but to agree to the Great Intelligence's terms, but before he heads for Piccadilly Circus he and Anne Travers finish work on their control sphere which will now make its Yeti follow their voice commands. While The Doctor and Anne Travers go looking for a suitable Yeti, that they can place their adapted control sphere in, Jamie and Colonel Lethbridge-Stewart set out to rescue Victoria.
They all end up being herded by the Yeti to Piccadilly Circus where, in the central ticket hall, they discover an enormous glass pyramid that is used to manifest the Yeti. Having no further use for Professor Travers the Great Intelligence abandons its control over him. It is then that it is revealed that a Staff Sergeant called Arnold has been the Great Intelligence’s human agent – so enabling the Great Intelligence to know the human’s every move.
The Doctor is then forced to enter the pyramid so that his mind can be drained. Fearing that The Doctor is about to be killed Jamie manages to break away and grabs a microphone that controls the Yeti – and so activates the Yeti with the adapted control sphere. The pyramid is destroyed in the ensuing scuffle along with the Yeti control spheres. With all the Yeti deactivated everyone is happy except for The Doctor. He explains that he had managed to sabotage the conversion headset which, if the device had been used, would have drained the Great Intelligence instead – but now the Great Intelligence is free once more.
With the Yeti defeated, and the web rendered harmless, The Doctor, Jamie and Victoria slip away and head back to the TARDIS leaving Colonel Lethbridge-Stewart to clear up the mess and return London and the Underground back to normal.