The necessary corpse

Nicholas Slade, an author and a scholar, could not correctly be called an amateur criminologist. However, he had an insatiable curiosity and certain situations so intrigued him that despite their hazardous nature he was constitutionally unable to refrain from investigating them. His curiosity was decidedly piqued when, as he prepared to keep a luncheon engagement with a department store magnate, Mr. Quinton, he was informed that his prospective host had rung up to say. "That he had received a letter informing him that he was to die at one-fifteen today and if, in the circumstances, you preferred to cancel the engagement, he would quite understand. But he hoped, nevertheless, that you would give him the pleasure of your company." Slade did not take Quinton's threatening letter too seriously, but after he had witnessed an attempt on Quinton's life the very moment he arrived at the store he realized that the letter writer was not joking.