London, 1985. The alien mercenary Lytton has been stranded here for nearly a year, but now he has a plan to escape. But how does it involve the Doctor's old enemies - and why are they on Earth at this point in history?

On Telos, the Doctor is reintroduced to the Cyber Leader and meets the Cryons, the planet's original inhabitants who will go to any lengths to get their world back!