[4][5] Made by Hammer Films, it was written by Ambrose Grayson and Roy Plomley, based on the popular long-running BBC radio series by Ernest Dudley and starring Cecil Parker.

[8] Private detective Doctor Morelle, who is intrigued by a case of a wealthy young woman who has mysteriously vanished, visits her gloomy mansion to investigate...

Valentine Dyall brings his imposing presence and intense manner to bear upon the part of Dr. Morelle with good effect, whilst Julia Lang is sufficiently witless as Miss Frayle.

"[11] Sky Movies wrote, "Each week from 1942 on, millions of radio listeners thrilled to the creepy adventures that presented 'the secret papers of perhaps the strangest personality in the history of criminal investigation.

The mysterious Dr Morelle and his always-in-peril Girl Friday, Miss Frayle, were a natural for films but, as with so many other popular radio sleuths, the British Cinema failed to do right by them even though the slightly sinister Valentine Dyall was perfect casting as the detective doctor.