The Doctor meet Professor Parry and his archaeologists on the planet Telos.
Professor Parry and his team begin to unlock the secrets of the Cybermen's tomb.
The Cybermen have risen from their hibernation and are intent on converting the humans.
The Cyber Controller has been revitalised after leaving the icy tomb, threatening to overpower his human foes.
The Doctor is accused of murder by Professor Travers who is in search of the legendary Yeti.
Jamie and Victoria make an incredible discovery in a cave on the mountain.
When a Yeti is captured by the Detsen monks, the Doctor discovers that it is a robot!
The old High Lama is in the control of the alien Great Intelligence which plans to invade Earth.
Discovering that his old friend is still alive after three hundred years, the Doctor goes to confront him.
As the Great Intelligence manifests itself on Earth, the Doctor makes an attempt to repel the evil entity.
The TARDIS arrives on Earth in the midst of a new ice age where a huge Ice Warrior is found frozen in the ice.
Varga, the Ice Warrior, has returned to life and has captured Victoria and takes her with him to the glacier.
Varga revives four fellow Ice Warriors from the ice and they begin to excavate their ship.
The Doctor goes to the Ice Warriors' ship in an attempt to broker a peace, but they do not trust him.
The Ice Warriors are preparing to fire their deadly sonic cannon at the Brittanicus Base.
The Ice Warriors invade the human's base, and it is up to the Doctor to repel them.
Arriving on an Australian beach in the future, the Doctor is mistaken for political leader Salamander.
Jamie and Victoria travel to Europe where they infiltrate Salamander's staff.
Jamie and Victoria befriend Fariah, intent on discovering the truth about Salamander.
Kent coerces the Doctor into agreeing to impersonate Salamander.
Impersonating Salamander, the Doctor infiltrates the research centre, but Benik becomes suspicious.
Astrid discovers the underground bunker and Salamander's secret.
The TARDIS lands in the London Underground, which is deserted.
The deadly web continues to advance in the tunnels of the Underground.
The Doctor meets Colonel Lethbridge-Stewart who takes control of the military operation against the Yeti.
The Doctor acquires a sample of the web, he, Jamie and Victoria return to the HQ to examine it.
Using Travers's body, the Great Intelligence demands that the Doctor allows his mind to be drained.
The traitor is revealed and all seems lost as the Doctor submits himself to the Great Intelligence's mind drain.
A gas refinery is experiencing problems and a sinister heartbeat is throbbing through the pipes.
As the situation worsens at the refinery, Chief Robson refuses to halt the gas flow.
Chief Robson refuses to acknowledge that matters have escalated beyond his ability to control them.
Investigating the impeller shaft, Van Lutyens is overwhelmed by the weed creature.
The deranged Chief Robson kidnaps Victoria in a helicopter and heads for the Control Rig.
The Weed has complete control of Chief Robson and threatens to conquer Earth.
The Doctor and Jamie are forced to abandon the TARDIS when the mercury fluid link explodes.
Jamie sabotages the Wheel's laser to save the TARDIS from destruction but places everyone in danger.
Cybermen are waiting for them on the Silver Carrier where a supply of bernalium is located.
The station is in danger of being destroyed by the approaching meteor storm.
The Cybermen reveal their plans to invade Earth, using the Wheel as a guiding beacon.
To defeat the approaching fleet of Cyber ships, the Doctor needs a component from the TARDIS.