England, the 1820s. As the Industrial Revolution gathers pace, the village of Killingworth is disturbed by crazed Luddite miners intent on smashing all machinery and engineers. But is there another cause of the situation?

The Master uses The Rani's mind-controlling parasites to keep a meeting of Earth's leading scientists from being cancelled, and helps her plant transformation land mines for The Doctor, as he continues to propose an alliance with her in ruling over Earth.

With the prosecution case concluded, at last the Doctor is able to present his evidence. It takes place in the future with a new companion and new problems.

As the Hyperion III continues its journey, more mysterious deaths occur.

A course change that takes the Hyperion III closer to a black hole could prove unwise when there are so many aboard ship with hidden agendas. Disappearances continue, a murderer remains at large, and one person finally crumbles under the strain of harbouring a guilty secret.

With factions vying for control of the ship, the Vervoids are found to be responsible for the many disappearances. Only the Doctor sees the fundamental but missed point as to why they can't be reasoned with or why they can't be allowed to arrive on Earth.

The alien world of Lakertya. With the aid of the savage Tetraps, the Rani has conquered this planet to allow her to continue her depraved biochemical experiments. But she finds herself needing the Doctor's assistance...

The Rani's impersonation of Mel backfires badly because Urak can't tell the difference, while the Doctor attempts to learn the secret of the Loyhargil.

The solstice nears, making it time for the Rani to bring her plans into fruition. The Doctor's sympathies for Beyus, ruler of the Lykertyans, are rather qualified. Beyus' heart is for his people yet something prompts him to collaborate fully in helping the Rani reach all her objectives. The answer, he's told, lies within the Center of Leisure.

The Rani, at last, links the Doctor into her great brain machine, the crowning jewel in her component packet of geniuses brought together to turn Lakertya itself into one vast cerebral mass capable of redirecting time anywhere in the universe, giving her absolute power over all creation.