As evidence for the defense at his ongoing trial, the Doctor presents an adventure from his future when he is travelling with a computer programmer named Mel. Answering a mysterious distress call from the space liner Hyperion III, they find that the passengers aboard include unscrupulous scientists, secret agents, saboteurs, thieves and a murderer. And lurking in the shadows are the Vervoids, the product of sinister botanical experiments, who will stop at nothing to destroy all non-plant life.
Colin Baker
as The Doctor
Bonnie Langford
as Mel Bush
Michael Jayston
as The Valeyard
Lynda Bellingham
as The Inquisitor
Honor Blackman
as Professor Sarah Lasky
Michael Craig
as Commodore Travers
Denys Hawthorne
as Rudge
Yolande Palfrey
as Janet
Malcolm Tierney
as Doland
David Allister
as Bruchner
Tony Scoggo
as Grenville
Arthur Hewlett
as Kimber
