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?