'Against a background of sinister mires and tors on Dartmoor, the author has woven a curious and intriguing story. The rambling old house contains a huge iron door which according to legend has hot been opened for centuries. A Cistercian brother accused of trafficking with Satan, was supposedly walled up behind this door. With the coming of the Clinton family, flickering scarlet lights are seen under the door and the shadow of the monk in dark garb haunts the corridors after dark. Into this brooding atmosphere comes Jeffrey Blackburn with his wife of twelve months, Elizabeth. They have been invited to the abbey by the Clintons. One of the guests is found murdered, amid clues point to the killer as 'Mr. Lynch'. Blackburn starts out on a trail that brings danger and thrills in its wake. What secret lies behind the strange barred door? Why does a mysterious figure in plus fours haunt the moors each night? And who is Mr. Lynch. [sic]'
Source:
'Broadcast Features', Cloncurry Advocate, 6 October 1939, p.7.
The Mysterious Mr Lynch served as a sequel of sorts to an earlier Jeffrey and Elizabeth Blackburn play, Revenge with Music, in as much as the comedy role from Revenge with Music, Detective Piggot, turned out to have a central (and entirely different) role in The Mysterious Mr Lynch, when he was revealed to be the mysterious eponymous criminal.
Max Afford noted that this revelation was one that brought a particularly strong outpouring of listener indignation ('Write Tough–but Aren't', Lockhart Review and Oaklands Advertiser, 23 January 1940, p.2).
Began broadcast on 9 October 1939, and ran for the following three months.