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