Originally Aired: May 21, 1957

A Case For Doctor Morelle #5, "The Blackmailer," Sir Clifford and Lady Forbes desperately seek Doctor Morelle's help when their daughter Cynthia attempts suicide twice by gas and refuses to explain why. The young woman recently returned from London, where she was supposedly in the company of Count Raymond Alvaro, a distinguished older Spaniard to whom she became attached during a family vacation in Spain. Doctor Morelle discovers that Cynthia cashed a cheque for two hundred and fifty pounds at her London bank before returning home, and the money has since vanished without a trace.

Working with Inspector Hood, Doctor Morelle investigates Cynthia's movements in London, interviewing staff at Christie's Hotel where she stayed. The trail leads to a darker truth about the charming Count Alvaro and his associate Harry Fox. Doctor Morelle deduces that Cynthia has fallen victim to a sophisticated blackmail scheme involving compromising photographs, preying on her youthful inexperience and fear of scandal. As the investigation unfolds, the detective must not only apprehend the criminals but also help the Forbes family navigate the delicate aftermath of their daughter's traumatic experience.