- Writer:
- Francis Durbridge
- Producer:
- Martyn C. Webster
- Settings:
- Frederick Knapman
- Mark Fenton:
- Hector Ross
- Mrs. Christie:
- Mary Horn
- Michael Christie:
- Brian Badcoe
- Detective Inspector Austin:
- Raymond Huntley
- Detective-Inspector Lester:
- Cecil Winter
- Detective-Sergeant Compton:
- Christopher Rhodes
- Colonel Wyman:
- Ivan Samson
- Robin Terry:
- David Peel
- Sister Rogers:
- Elizabeth Maude
- Wade:
- Reginald Hearne
- Dr. Andrew Sefton:
- Hugh Kelly
- Sir Oliver Peters:
- Arthur Ridley
- Linda Brooks:
- Pamela Galloway
