Jamie and Zoe attempt to recover the time vector generator while the Cybermen realise the Doctor is on the Wheel and make him their prime target.
The Cybermen gain control of more members of the Wheel crew and the Doctor realises the only way to stop them is for Jamie and Zoe to make a dangerous space walk.
The Cybermen instruct their human slaves to smuggle them onto the Wheel while the Doctor attempts to convince Bennett of the threat they pose.
Jamie sabotages the Wheel's x-ray laser, unknowingly giving the Cybermen an opportunity to reach the Wheel.
The Doctor and Jamie are brought aboard the Wheel where Jamie is horrified to learn the crew plan to destroy the Silver Carrier with the TARDIS on board.
The Doctor and Jamie arrive on a mysterious spacecraft whose only occupant is a dangerous Servo Robot.
The Doctor and Jamie rescue Victoria from Robson and realise they can destroy the Weed Creature with sound waves.
With the Weed Creature poised to burst out of the pipeline and attack the base, an encounter with Oak and Quill gives the Doctor a vital clue about its weakness.
Van Lutyens' investigation of the base of the impeller places the Doctor and Jamie in danger from the Weed Creature.
While the Doctor begins his investigation into the weed creatures, Robson is attacked by one at the refinery.
Harris asks for the Doctor's help with Maggie, while Van Lutyens and the Chief Engineer attempt to find out what is blocking the impeller.
The Doctor, Jamie and Victoria are taken prisoner by the staff of a gas refinery, who have lost contact with their drilling rigs and experienced mysterious drops in pressure.
The Doctor and his friends are held prisoner by the Intelligence and their only hope lies with Jamie, Arnold and a reprogrammed Yeti.
Victoria and Travers are held prisoner by the Great Intelligence, who is planning to drain the Doctor's mind.
With Travers having been captured by the Yeti, the Doctor attempts to find a way to gain control of the robots while Lethbridge-Stewart tries to recover the TARDIS.
The Doctor and Victoria are taken back to the Goodge Street base by Colonel Lethbridge-Stewart where the Doctor becomes convinced there is a traitor in their midst.
Jamie and Victoria are reunited with Travers before Jamie joins the soldiers in attempting to find out what has happened to the Doctor.
The TARDIS becomes trapped in space before ending up in an underground station of a mysteriously deserted London.
The Doctor discovers the true link between Salamander and Kent while Astrid tries to convince the shelter inhabitants they have been lied to.
The Doctor persuades Bruce to help him infiltrate Salamander's research centre while Salamander takes drastic action to prevent Swann finding out the truth.
Fariah brings the Doctor and Kent evidence of Salamander's activities but then they come under attack from Benik.
Jamie and Victoria join Astrid into attempting to rescue Denes but Salamander becomes suspicious of them.
Jamie and Victoria agree to accompany Astrid to Hungary to observe Salamander's activities.
After the Doctor is attacked by a group of mysterious gunmen, he discovers he is the physical double of the famous scientist Salamander.
The Doctor and Victoria attempt to force the Ice Warriors to surrender control of the ioniser before the ice flow destroys them.
The Doctor and Victoria are both held prisoner by the Ice Warriors as Varga decides to take over Brittanicus.
The Doctor leaves the base to try and find Jamie and Victoria while Storr tries to do a deal with the Ice Warriors.
Jamie and Arden venture out to rescue Victoria only to find the rest of the Ice Warriors are now active.
Varga revives and takes Victoria hostage as he works to revive his crew while the Doctor and Jamie find Penley stealing medical supplies.
The Doctor, Jamie and Victoria are brought to a base which is attempting to halt the flow of the Second Ice Age.
With the Great Intelligence on the verge of becoming corporeal, the Doctor challenges Padmasambhva to a mental battle in order to defeat it.
Victoria falls under the mental influence of Padmasambhva as the Yeti attack in order to drive the monks from the area.
The Yeti escapes from the monastery and Victoria and Thonmi are accused of assisting it, while the Doctor and Jamie endure a perilous journey back across the mountains.
While the Doctor and Jamie return to the TARDIS for equipment, the control sphere Jamie brought to the monastery is reactivated.
Jamie and Victoria make their way to the monastery shortly before it is attacked by the Yeti.
When the TARDIS materialises in the Himalayas, the Doctor decides to pay a return visit to the nearby Det-Sen monastery only to be accused of murder.
Klieg attempts to do a deal with the Cybercontroller while the Doctor tries to find a way to refreeze the Cybermen permanently.
The Cybermen have been revived and plan to convert the archeologists into their own kind, prompting Hopper to attempt a rescue.
The archaeologists learn they are stranded on Telos and Klieg suggests they use the opportunity to explore the Cybermen's tombs.
The Doctor, Jamie and Victoria arrive on Telos, where an archaeological group are exploring the Tomb of the Cybermen. But are the Cybermen as dormant as they believe?
