Back in the 17th Century, the Magician's apprentice tries to harness the power of electricity but an explosion in his lab accidentally creates a dangerous substance called Black Gold and forces the Magician back to his own time, losing his precious gold pendulum. Meanwhile, in the present, a large corporation is planning to build a theme park close to Golden Valley, which would destroy the rare and beautiful surroundings.

• Ian Richardson
• Siân Phillips
• Stephen Fry