Edward Stevens, an editor at Herald and Son's publishing house, is on the train home, recounting the story of the death of the rich uncle of his neighbor, Mark Despard.

And after he died, under his pillow was found a strange piece of string, tied in nine knots, a witch's ladder.

The book, by noted true crimes author Gaudan Cross, is on murders by poison, and it begins with the trial and execution of Marie d'Aubray in 1861.

Mark explains that he believes his uncle was murdered, and that he, Partington, and Stevens, are going to dig up the body and perform an autopsy.

"A stunning situation to start with, which leads to steadily more complicated problems -- all perfectly clear, thanks to the art of this master of plotting ... we are also given a rationally possible explanation of the events, but the odor of brimstone overcomes the factual sense and renders the story a hybrid.

[3] A French-Italian-German film of the same name (directed by Julien Duvivier and written by Charles Spaak) was released in 1962.

[4] A 3-part TV dramatization was broadcast by RAI in summer 1979, with the title La dama dei veleni.