The TARDIS takes the newly regenerated Doctor to Earth to begin his exile.
A recovered Doctor escapes the hospital and joins UNIT in their investigation.
Sam Seeley has found one of the meteorites but the Autons want it back and are closing in.
The invasion begins as Auton shop dummies come to life and attack the public.
UNIT are summoned to Wenley Moor research station which is experiencing mysterious power losses.
Investigating the caves, the Doctor is attacked by a dinosaur-like creature.
The creature from the caves, wounded and dangerous, is on the loose on Wenley Moor.
Fearful of a war breaking out between the Silurians and mankind, the Doctor attempts to make peace.
When the Silurian leader is killed, all hopes of peace are lost.
As the Silurian plague quickly spreads, the Doctor desperately searches for a cure.
With the antidote to the plague found, the Silurians retaliate and take over the research centre.
UNIT is called in and the Doctor learns that someone is sending messages to the vessel.
Recovery 7 has returned to Earth but the UNIT convoy transporting the capsule is ambushed.
The recovery capsule is empty with the astronauts seemingly kidnapped.
Liz has been captured by Reegan who is holding the three aliens captive.
The Doctor prepares to pilot the Recovery 7 ship into space, but Reegan sabotages the fuel supply.
On board a vast spacecraft, the Doctor meets the alien captain who demands the return of the ambassadors.
General Carrington is behind the kidnapping of the ambassadors and intends to turn the world against the aliens.
UNIT are at a project run by Professor Stahlman who intends to penetrate Earth's crust.
The green slime oozing from the drill head is transforming men into monsters.
Transported to a parallel world, the Doctor discovers that England is under military rule.
In the parallel world, the drilling project is about to penetrate the Earth's crust.
In the parallel world, Earth’s crust has been penetrated, releasing terrible forces from within the Earth.
As the parallel Earth faces destruction, the Doctor is desperate to return to his world to warn them of the danger.
The Doctor has escaped the doomed, parallel Earth and attempts to put a halt to the drilling project.