- Writer:
- Francis Durbridge
- Producer:
- Martyn C. Webster
- Settings:
- Frederick Knapman
- Mark Fenton:
- Hector Ross
- Dr. Andrew Sefton:
- Hugh Kelly
- Harrison:
- Roger Delgado
- Wade:
- Reginald Hearne
- A nurse:
- Nancy Manningham
- Sir Oliver Peters:
- Arthur Ridley
- Morgan:
- Duncan McIntyre
- Linda Brooks:
- Pamela Galloway
- Detective Inspector Austin:
- Raymond Huntley
- Police Sergeant:
- Stanley Groome
- Detective Inspector Lester:
- Cecil Winter
- Sister Rogers:
- Elizabeth Maude
- Robin Terry:
- David Peel
- Michael Christie:
- Brian Badcoe
- Collins:
- Charles Leno
- Detective Sergeant Compton:
- Christopher Rhodes
- Mrs. Christie:
- Mary Horn
