story?

When the Doctor and Ruby arrive on Cavia, they meet a gentle local who is certain that she has been taken for study by creatures from the stars. The Doctor is concerned to find mysterious meteors appearing in the sky, while strange robotic creatures crowd the forests, watching everything and waiting for… what?

Who is interested in Cavia, and why? What is the sinister truth of the abductions? The Doctor and Ruby must discover the secrets of this mysterious world – and those who would seek to destroy it…