The year is 1815 and Captain Hugh Austen of the Grenadier Guards is attending a ball before he leads his troops to face Napoleon at Waterloo. A young woman asks his help and the vanishes, leaving only a miniature portrait of herself.

The woman is connected with a Satanic Man in Black who is rumored to practice Unhallowed Arts. Soon, Austen discovers that the mysterious woman was publicly executed for murder a year earlier. Has she been restored to life by black magic? Has she guilty or innocent of stabbing a miserly woman to death? Who is trying to stop Austin from finding the truth?

John Dickson Carr, the master of impossible crimes, eerie atmosphere, and historical romance, leads us through Regency England—its high society and low, its dandies and its fair charmers, its fascination with duelling and the newfangled gas-ballooning—until, in the presence of H.R.H. the Princes of Wales himself, Austen discovers who dared to Speak of the Devil.

Written in 1941 and broadcast in eight parts on the BBC, Speak of the Devil is John Dickson Carr at his ingenious best.