Guest Stars Lynda Bellingham as The Inquisitor Michael Jayston as The Valeyard Honor Blackman as Professor Lasky Michael Craig as Commodore Travers David Allister as Bruchner Sam Howard as Azta Malcolm Tierney as Doland Arthur Hewlett as Kimber Denys Hawthorne as Rudge Leon Davis as Ortezo Yolande Palfrey as Janet Simon Slater as Edwardes Barbara Ward as Ruth Baxter Peppi Borza as First Vervoid Bob Appleby as Second Vervoid Uncredited Robert Goodman as Hyperion III Officer Richard Bonehill as Hyperrion III Guard
