Rothwyn and Eldred, a couple living in a modern apartment with a baby, are from the 35th Century, the apartment is their time capsule, which is situated and cloaked on the roof of a present-day tower block; in a test to live as 20th century humans. But trouble starts when the couple discover that they can neither contact their controllers in the future nor two other similar time capsules in the present day. The biomechanical system that runs the capsule has an agenda of its own, one of vengeance. This time, Sapphire and Steel have help in the form of Silver, an inter-dimensional operator.

• Joanna Lumley
• David McCallum
• David Collings
• Christopher Fairbank