The Master arrives on Earth in his TARDIS, camouflaging it as a horse box in a Circus.
The Master, has assumed control at the plastics factory and is manufacturing new lines of living plastics.
The Doctor and the Brigadier trace the Master to the plastics factory but they are too late.
The Doctor catches up with his old enemy, the Master. Can anyone stop the Nestene Consciousness?
The Doctor and Jo watch a demonstration of the Keller Machine which can extract evil impulses from criminals.
A full scale riot takes place at the Prison and Jo is taken hostage.
The Master is behind the Keller Machine and uses it to recruit the rioting inmates at Stangmoor Prison.
The mind parasite within the Keller Machine becomes too powerful for the Master to control.
The Master forms an uneasy alliance with the Doctor so that between them they can subdue the Keller Machine.
The Keller Machine breaks free of the Doctor's restraining device. The Doctor turns it against the Master.
Axos, a living spacecraft, lands and offers Earth a new energy source - Axonite.
The Doctor quickly discovers that the miracle Axonite substance is not as benign as it seems...
Axos puts its plan to drain the Earth of its energy in motion. The Brigadier must turn to an unlikely ally to stop it…
The Claws of Axos are deeply embedded in the Earth's carcass.
The Doctor and Jo arrive on a barren world in the far future where human colonists are scratching a living.
The Interplanetary Mining Corporation, represented by Captain Dent, arrives on the planet.
When Jo attempts to break into the IMC ship to find incriminating information, she is captured and held hostage.
The Master arrives, posing as an adjudicator from Earth who has come to settle the dispute.
With Jo held prisoner in his TARDIS, the Master forces the Doctor to take him to the underground city.
In the underground city, the Doctor and the Master confront the guardian of the doomsday weapon.
The Doctor tries to prevent Professor Horner from breaking into an ancient barrow near the village of Devil's End.
The Doctor and Jo return to the barrow where they are confronted by the gargoyle, Bok.
The Doctor attempts to help the Brigadier penetrate the heat barrier but is attacked by the Master's servant.
The Doctor is captured by the villagers who are under the Master's control.
UNIT have penetrated the heat barrier and launch an attack on the gargoyle, Bok.