[1] It is the forty third in his long-running series of novels featuring Lancelot Priestley, a Golden Age armchair detective.

[3] Doctor Richard Mawsley is found dead in the consulting room of his Harley Street practice, apparently from strychnine.

Inspector Waghorn of Scotland Yard takes up the case, but it requires the particular brilliance of Priestley to demonstrate that this strange case was neither accident, suicide or murder.

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