A Dinosaur Attacks

The TARDIS materialises in what The Doctor, and his companion Sarah Jane Smith, soon realise is a deserted London. Curious as to what is going on they see a car but it does not stop so they follow it and soon discover its driver robbing a jeweller's. On being discovered the looter runs off but a screech of tyres and a bloodcurdling roar brings them outside to find the robber dead and the car's bonnet smashed in. The Doctor and Sarah then follow a land rover to a garage and disturb two more looters. To The Doctor’s surprise they are attacked by a flying creature that The Doctor identifies as being a pterodactyl. They escape by taking the land rover but are soon stopped by UNIT soldiers who, on discovering stolen gods in the back, arrest them and take their photographs in preparation for a military trial.

These photographs soon arrive at UNIT’s headquarters where thankfully Sergeant Benton recognises The Doctor and Sarah. The Brigadier, after being notified of The Doctor’s arrival in London, sends a despatch rider to fetch them. But after being found guilty of looting, and sentenced to be held in a military detention centre, The Doctor and Sarah manage to escape unaware that The Brigadier has arranged for them both to be freed. The Doctor and Sarah end up hiding in a warehouse where they meet a peasant from the time of King John who then fades away in a time eddy. The Brigadier then arrives and they all return to UNIT headquarters.

It is then that The Doctor and Sarah discover that UNIT are trying to find out why dinosaurs have been appearing all over Central London but it seems that The Brigadier is no nearer a solution. In overall charge is General Finch, but he refuses to listen to The Doctor's theories that someone in London is behind the appearances of the dinosaurs and other elements from the past. The Doctor therefore starts to build a stun-gun which he can use to knock out a dinosaur so that he can then monitor it when it vanishes – so enabling him to trace the source of the power used to transport it to the present day.

Standing Guard

What The Doctor, The Brigadier and UNIT do not realise is that a scientist called Professor Whitaker is engineering the appearances. Working with a man called Butler they are keeping Central London empty of people. UNIT officer Captain Mike Yates is also in league with them. He warns Professor Whitaker of The Doctor's plans and so Professor Whitaker gives Captain Mike Yates a small device which will render The Doctor's stun-gun ineffective. And so when a seemingly docile brontosaurus appears The Doctor approaches it so that he can stun it unaware that his gun has been sabotaged. However, without warning the brontosaurus vanishes and a tyrannosaurus appears instead. Realising that his actions has put The Doctor in grave danger Captain Mike Yates removes the device from the gun and stuns the creature before it can harm The Doctor. With the large dinosaur moved to a hangar The Doctor places his detection devices around it. On learning what has happened Professor Whitaker instructs Captain Mike Yates to sabotage The Doctor's detection equipment.

On discussing who could be behind the manipulation of time Sarah remembers hearing about Professor Whitaker’s experiments from a story she worked on but no-one will follow up her suspicions. Sir Charles Grover MP, who is still in London, claims Professor Whitaker was a crank but General Finch seems interested and also arranges for Sarah to obtain a special pass so that she might take photographs of the captured tyrannosaurus. But the flash on Sarah’s camera revives the dinosaur and she finds herself trapped in the hanger. The Doctor comes to her rescue. He also discovers that the chains that held the creature had been cut and that all The Doctor's equipment had been sabotaged. Realising that someone within UNIT is working against him The Doctor decides to build a portable device to try and locate the power source – which he deduces is probably a small nuclear reactor. Sarah remembers about nuclear reactors being built into government bunkers and goes to see Sir Charles Grover. The reactor is actually under the building in which Sir Charles Grover is based and he tricks Sarah into entering a concealed lift which takes her to the underground base. There she is hypnotised with flashing lights.

The Doctor, Sarah and The Brigadier

When Sarah wakes, she appears to be in a spacecraft which she is informed is some three months out from Earth, en-route for a planet dubbed New Earth. On board the space ship she meets Mark, Ruth and Adam who are three of 200 people, on seven ships, heading for the planet. Sarah though realises that all this is untrue when she feels the bump sustained in the hangar still on her head. Ruth is determined that Sarah must be re-educated and she is locked in a room which plays a continuous film of the pollution on Earth.

Meanwhile in a deserted London, The Doctor travels in his new car - a futuristic hovercraft vehicle - with his tracking device until he locates the power source in a London Underground station. He sees Butler enter and use a lift disguised as a janitor's cupboard to descend into an underground shelter. The Doctor follows him but is detected and routed back to the lift which takes him back up to the Underground station. On exiting the lift The Doctor is attacked by another pterodactyl before he manages to escape. On returning to the UNIT headquarters, The Doctor receives a phone call from Professor Whitaker telling The Doctor that he will meet him in the hangar. When he arrives The Doctor realises that someone is trying to discredit him when Professor Whitaker summons a stegosaurus just as General Finch bursts in, accusing The Doctor of being behind the appearances.

Back on the spacecraft, Ruth tells the others that Sarah will have to be eliminated if she cannot be re-educated. Mark goes to warn Sarah and helps her to escape. On discovering that the flight equipment on the spacecraft does nothing, she proves to Mark that it is all a fake by leaving through the airlock. She returns to UNIT headquarters but finds no-one there except for Private Bryson. It appears that General Finch has given orders that The Doctor, whom Sergeant Benton allowed to escape, be shot on sight, and The Brigadier and Sergeant Benton have gone to try and find him first. General Finch arrives and Sarah confides in him. She takes him back to Sir Charles Grover's office where he pulls a gun on her and so Sarah finds herself a prisoner once more.

The Doctor and The Brigadier

Sir Charles Grover then orders a final wave of dinosaurs to ensure that no-one remains in London. He also gets General Finch to order all the UNIT and government troops to pull out. His plan is to roll back time on Earth so that those within a protective field of influence will arrive at an earlier 'golden age'. Sarah is then locked in a store room but manages to escape through a ventilation shaft. She returns to the fake spaceship but Ruth has her and Mark locked up. Adam is suspicious and sends a message to Sir Charles Grover who is allegedly on one of the other ships. He arrives in a space suit and admits his plan to Sarah and Mark, unaware that Adam is listening at the door. When he has gone, Adam releases Sarah and Mark and they head for the airlock. Sarah opens it and the rest of the passengers follow her out, determined to confront Sir Charles Grover.

The Doctor meets up with The Brigadier and they both return to UNIT headquarters. There, Captain Mike Yates threatens them with a gun, but Private Bryson inadvertently distracts him allowing the others to overpower him. The Doctor and The Brigadier then head for the Underground station with explosives and rope. On arriving at the Underground station The Doctor and The Brigadier blow up the lift entrance enabling The Doctor to descend down the lift shaft. In the underground base The Doctor knocks Butler out and then confronts Sir Charles Grover and Professor Whitaker just as Sarah, Ruth and the others arrive. When The Brigadier and Sergeant Benton arrive shortly afterwards Professor Whitaker takes the opportunity to start his machine. Time stands still for everyone except for The Doctor who manages to switch the machine off. He then reverses the polarity but this allows Sir Charles Grover to lunge at the controls. As he struggles with Professor Whitaker, they and the machine vanish into the past.

With the demise of Sir Charles Grover and Professor Whitaker, and as there is no longer a threat of any more dinosaurs arriving, The Brigadier starts to arrange for the capital to return to normal. He also grants Captain Mike Yates extended sick leave and the opportunity to retire quietly. At the same time The Doctor makes his own plans for another trip in the TARDIS and tries to persuade an initially reluctant Sarah to go with him to the planet Florana...