The Cybermen

The TARDIS takes The Doctor and his companions Ben Jackson and Polly Wright to the South Pole in the year 1986. They realise that they have landed close to a Space Tracking station and at a point where the personnel, under the command of General Cutler, are engaged in trying to talk down a manned space capsule that has got into difficulty.

Unusual readings on the spaceship's instruments lead to the discovery of a new planet suddenly approaching Earth. The spaceship begins to experience power losses, and the Snowcap personnel begin arrangements to abort its mission.

The Doctor instantly recognises this new planet – revealing that it is called Mondas and that it is Earth's former sister planet. He also warns that its inhabitants will soon be visiting Earth. True to his prediction, three robotic creatures land outside, killing the guards and disguising themselves in the dead men's furs to gain access to the Snowcap base.

Ben with The Doctor

While everyone is distracted by their efforts to land the manned space capsule safely, the creatures are easily able to take over the base at a crucial moment in the space capsules recovery. The base personnel and Polly plead with the invaders to allow them to save the lives of the crew, but the creatures are not interested as the lives of the crew are irrelevant to them. This is because they are Cybermen, who were once like human beings, but gradually replaced their bodies with mechanical parts, including eliminating the ‘weakness’ of emotion from their brains. The Cybermen eventually allow the Snowcap personnel to make contact with space capsule but it is too late as the ship is dragged away by Mondas and explodes.

The Cybermen then explain that their home planet, Mondas, is absorbing energy from Earth and will soon destroy it. To the horror of Polly it is also revealed that their prime propose is to take humans back to Mondas and then turn them into Cybermen.

Cyberleader Krang

Fortunately, Ben, who has been imprisoned, after attempting to kill a Cyberman, manages to escape and kill the Cyberman that has been guarding him. Stealing the Cyberman’s weapon Ben sneaks back into the Tracking Room and, unseen by the two remaining Cybermen, is able to pass the cyberweapon to General Cutler who is able to kill the two Cybermen.

Deciding that it is time to fight back, General Cutler orders the use of a powerful Z-bomb to destroy Mondas. However, Ben argues against using the bomb, saying that Mondas might destroy itself anyway when it absorbs too much energy. The chief scientist at Snowcap, Doctor Barclay, is also concerned, saying that the radiation caused by the exploding planet would cause great loss of life on Earth. Un-swayed though, General Cutler orders Ben to be imprisoned in a cabin with The Doctor, who is unconscious and seemingly ill.

Doctor Barclay goes to Ben and tells him how to sabotage the rocket to prevent it from reaching Mondas and so when the Z-bomb is launched the engines fail. This though enrages General Cutler who threatens to kill Ben, Doctor Barclay, and The Doctor, who has now regained consciousness. But before General Cutler can carry out his revenge he is shot himself. To the horror of those around him they realise that another squad of Cybermen have arrived and they want the sabotaged Z-bomb repaired – and they force the Snowcap personnel, along with Ben, to do this by taking Polly back to their spaceship as a hostage.

A Cyberman and General Cutler

As the Cybermen start to take over the world, The Doctor realises that their plan is to destroy the Earth with the Z-bombs, thus saving Mondas. In the radiation room, Ben realises that the reason why they need to use humans to do this work rather than doing it themselves is that they are highly susceptible to radiation and with the help of Doctor Barclay they use some of the rods from the reactor chamber as a portable weapon against the Cybermen. This proves highly successful them to regain control of the base. More Cybermen enter the Tracking Room, but just at that moment Mondas explodes, and all the remaining Cybermen collapse and die, having been totally dependent on their planet for energy.

With the threat over Ben, Polly and The Doctor are reunited. But all is not well as it seems that something is very wrong with The Doctor. Back inside the TARDIS The Doctor falls to the floor, and before the astonished eyes of his two companions, he is transformed into that of a much younger, dark-haired man.