- Author:
- Sir Arthur Conan Doyle
- Dramatised by:
- John Hawkesworth
- Music:
- Norman Kay
- Designer:
- Derek Dodd
- Producer:
- Harry Moore
- Director:
- Piers Haggard
- Tom Crabbe:
- Keith Buckley
- Vicky Crabbe:
- Michele Dotrice
- Philip Hardacre:
- Michael Latimer
- Monkhouse Lee:
- Christopher Matthews
- Dr. Markham:
- Iain Cuthbertson
- Norah:
- Adrienne Frame
- Dr. O'Connell:
- Mike Pratt
- Woman in pub:
- Kathleen Heath
- Blonde girl in pub:
- Lynne Ashcroft
- First policeman:
- Dennis Adams
- Second policeman:
- James Donnelly
- Schoolboy:
- Alan Williams
- Woman in hat:
- Mary Hignett
- Boatman:
- Norman Stanley
- Waiter:
- Larry Martyn
- Landlady:
- Nora Gordon
- First reporter:
- Timothy Harley
- Second reporter:
- Roger Worrod
- Police Inspector:
- Fred McNaughton
