Mary Tamm (Romana), Madeleine Potter (Lady Ferril)
The search for the fourth segment of the Key to Time brings the Doctor and Romana back to Earth in the present day.
In a small village in Norfolk, former astronaut Lady Millicent Ferril has established an observatory, tracking a meteorite from the Cronquist System. It is a meteorite that almost killed her years before - and perhaps left her not entirely human.
As Ferril's power grows, so does her influence. She can control metal. And anything metal - from a suit of armour to a bicycle - is now lethal...
(Duration: 60' approx)