Guest Stars Walter Henry as Primord Roy Scammell as RSF Sentry Peter Thompson as Primord Philip Ryan as Primord Sheila Dunn as Dr. Petra Williams Sheila Dunn as Petra Williams Keith James as Patterson Walter Randall as Harry Slocum Christopher Benjamin as Sir Keith Gold Dave Carter as Primord Pat Gorman as Primord Derek Ware as Private Wyatt David Simeon as Private Latimer Derek Newark as Greg Sutton Olaf Pooley as Professor Stahlman Olaf Pooley as Director Stahlman Ian Fairbairn as Bromley
