The TARDIS arrives on the Moon in the year 2070.When Jamie is injured, the other travellers are forced to seek the help of a moonbase afflicted with a space plague.

The Doctor and his friends attempt to convince the Moonbase crew that the Cybermen are responsible for the disappearances and find a cure for the plague.

The Cybermen take over the Moonbase and begin using the Gravitron to attack Earth but Polly, Ben and Jamie come up with a way to fight back.

With the Cybermen preparing to launch a full attack, the Doctor and his friends must keep the Moonbase and the Gravitron out of their hands until help arrives from Earth.

The archaeologists learn they are stranded on Telos and Klieg suggests they use the opportunity to explore the Cybermen's tombs.

The Cybermen have been revived and plan to convert the archeologists into their own kind, prompting Hopper to attempt a rescue.

Klieg attempts to do a deal with the Cybercontroller while the Doctor tries to find a way to refreeze the Cybermen permanently.

The TARDIS arrives on the planet Dulkis where the Doctor, Zoe and Jamie decide to have a quiet holiday. Only to find the Evil Dominators and their robotic slaves, The Quarks have arrived on a radioactive island, where they plan to detonate a bomb in the planet's core, which will turn the entire planet as source of radioactive fuel for their invasion fleet.

The Doctor and Jamie are captured by the Dominators, who subject them to an intelligence test, while Zoe and Cully attempt to convince the Dulcian council of the threat.

Zoe and Cully are captured by the Dominators and put to work alongside the survey team while the Doctor and Jamie decide to return to the island to help.

The Doctor and Zoe are interrogated by Rago, who is planning to present his terms to the Dulcian council, while Jamie and Cully try to find a way to strike back against the Quarks.

Jamie and Cully manage to rescue the Doctor's party and together they try to find a way to stop the Dominators before they destroy the entire planet.