Invasion of the Dinosaurs
Featuring: Third Doctor, Sarah Jane Smith, Brigadier Lethbridge-Stewart, Sergeant Benton, Mike Yates
The TARDIS materialises in a completely deserted London. It turns out that UNIT has arranged the evacuation of London because of Dinosaur attacks. The Doctor theorises that the Dinosaurs are deliberately being brought forward in time. Sarah investigates the scientist Whittaker, who has written about time travel and some cold-war bunkers. She is captured and hypnotised before waking up on what appears to be a spacecraft three months out from Earth. This craft contains colonists who are planning to create a new human society free from pollution. She soon realises that three months have not passed, and eventually persuades the other passengers of the truth.
Meanwhile the Doctor has discovered that those behind the dinosaur attacks are planning to roll back time to a "golden age "of history, where the "colonists" can restart human civilisation. The Doctor is too late to stop the process beginning, but interferes with the machinery. This sendsthe plot's instigators, Whittaker and Grover, into the past. The Brigadier offers Mike Yates, who had been involved in the plot, the opportunity for a quiet exit from UNIT. The Doctor tries to persuade Sarah to join him on a holiday trip to Florana.