The Doctor and Sarah arrive safely back on Earth — or do they?

Why does the mysterious soldier march straight over a cliff — and then reappear unharmed?

Why are they attacked by the 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 their best friends suddenly trying to kill them?

The Doctor has stumbled on a cunning alien plan to take over the Earth. Will he be in time to defeat the deadly Kraals and their terrifying android invasion?

Novelization of the Doctor Who TV series; four episode story "The Android Invasion" (1975), script by Terry Nation.