The huge, octopus-like Kroll lives deep in the swamps of the humid, steamy planet Delta Three. To the native swamp-warriors, Kroll is an angry mythical god. To the money-grabbing alien technicians, it is a threat to their profit-making scheme. When the Doctor and Romana arrive, in search of another segment of the Key to Time, they have to face the suspicion of the lagoon dwellers, the stupidity of the technicians and, finally, the power of Kroll itself.

On the planet Tigella, the Savants and the Deons are irrevocably opposed on one crucial issue: the Dodecahedron, mysterious source of all their power. To the Savants, it's a miracle of science to be studied and used to benefit all. To the Deons, it's a god, and not to be tampered with. When the power source begins to fluctuate, the whole planet is threatened. Zastor, Tigella's leader, welcomes the Doctor and invites him to arbitrate; yet the Time Lord may not be all he seems.

Geoffrey Beevers reads this exciting novelisation of a classic TV adventure for the Fourth Doctor. The Doctor is suddenly summoned to Gallifrey, the home of the Time Lords, where his ghastly hallucinations of the president’s assassination seem to turn into reality. When the Doctor is arrested for the murder, a hideous, dark, cowled figure is gleefully watching in the shadows. In a battle of minds, the Doctor faces renegade Time Lord the Master inside a nightmare world created by his old enemy’s imagination.

The Doctor and Sarah arrive safely back on Earth—or do they? Why does the mysterious solder march straight over a cliff, and then reappear unharmed? Why are they attacked by sinister mechanics with built-in guns for hands? Why is a picturesque country village at first deserted, then filled with mindless zombies? And why are the Doctor and Sarah's best friends trying to kill them? Will they be in time to defeat the deadly Kraals and their terrifying android invasion of Earth?

An unabridged reading of the final adventure for the 4th Doctor, novelised by Christopher H. Bidmead from his original TV scripts. The meddling presence on Earth of the Doctor's arch enemy, the Master, ensures the disruption of normality. Even he is horrified by the threat of total chaos he unintentially precipitates - until he finds a way to turn the imminent destruction of the universe to his own advantage. But the cost for the Doctor himself is terrible.