Maurice Colbourne

The Cybermen are hiding in the London sewers and turning humans into semi-cybernetic slaves. On Telos two slaves make a bid of freedom and find a way to escape the planet for good.

On Telos the Doctor is reintroduced to the Cyber Leader and meets the Cryons, the planet's original inhabitants who want their planet back and will go to any lengths to do so.

Davros is held captive aboard a prison in space but the Daleks launch a rescue attempt.

As survivors of the prison station fight the invaders, Dalek agents on Earth take steps to protect the time corridor being used by the Doctor's friends.