Cornerstone: Re-enter Sir John (1932).
Note: This continues my occasional series on the Haycraft-Queen Cornerstone list (those mysteries deemed essential by Howard Haycraft and Ellery Queen).
Dane, Clemence [Winifred Ashton], and Helen Simpson [Helen de Guerry Simpson Browne]. Re-enter Sir John (1932)

“Circumstances,” went on Sir John, “are often bare-faced liars.”
(Re-enter Sir John 63)

Sir John Saumarez, master thespian and sometime sleuth, investigates an accusation of cheating at cards against his protégé, which turns deadly when the protégé’s landlady is murdered on a London street. The book’s extraordinary climax features Sir John confronting the killer via a silent film he has made with his evidence.

Sir John debuted in Enter Sir John (1928), which was adapted as the Hitchcock film Murder! (1930), and also appears in Author Unknown (aka Printer’s Devil, 1930) and ’Vantage Striker (aka The Prime Minister Is Dead, 1931, written by Helen Simpson). Sadly, none of these works, nor Re-enter Sir John, are currently in print (hint to mystery small presses).

British artist and writer Clemence Dane (1888-1965) wore many hats in her life. Called “a gallant old girl” by her longtime friend Noël Coward and believed to be the model for Madame Arcati in Coward's Blithe Spirit, she wrote the play A Bill of Divorcement (later made into a film starring Katharine Hepburn) and won an Oscar for her original story for Perfect Strangers (aka Vacation from Marriage, 1945) with Robert Donat and Deborah Kerr. She also was a contributor to the Detection Club’s round-robin mystery The Floating Admiral (1931).

Australian-born Helen Simpson (1897-1940) founded the Oxford Women’s Dramatic Society and published novels, plays, and poems. She contributed to the Detection Club work Ask a Policeman (1933). Besides the Sir John series, her other mystery work includes Acquittal (1925); Cups, Wands, and Swords (1927); and Under Capricorn (1937), the latter made into the Hitchcock film of the same name. She married Denis John Browne, who became an eminent surgeon for London’s Great Ormond Street Hospital for Children and was the nephew of Australian novelist Rolf Boldrewood.