The Secret Adversary
Agatha Christie began writing "Black Coffee" in 1929, feeling disappointed with the portrayal of Hercule Poirot in the previous year's play "Alibi", and being equally dissatisfied with the motion-picture adaptations of her short story "The Coming of Mr. Quin" and her novel "The Secret Adversary" as "The Passing of Mr. Quin" and "Die Abenteurer GmbH". According to the foreword to the current HarperCollins edition of "Black Coffee" in its novelised form, she finished writing the play in late 1929.