Suspense's "The Man Who Knew How" was adapted from the short story by Dorothy L. Sayers, which was first published in Harpers Bazaar in February 1932. Suspense's version adds a little more to the ending, but otherwise, it is presented as written. The original story is available online at Google Books.
As the episode opens, Mr. Pender strikes up a conversation with a fellow passenger on a train. He offers the man a mystery to read, but the stranger declines the offer. The murders in mystery books are far too inadequate for him because the criminals always get caught. He is more interested in the murderers who don't get caught. Then, he mentions that one could easily kill someone without detection by using a few simple chemicals.
Mr. Pender is taken aback, but intrigued by this unusual man, who seems to know exactly how a perfect murder can be achieved.
In the days that follow, Mr. Pender becomes aware of a number of deaths where the victims died exactly in the same way that the stranger had mentioned. Is the man on the train responsible for their deaths?
"The Man Who Knew How" was adapted for radio by Evelyn Keller and produced/directed by William Spier. Charles Laughton starred as Pender and Hans Conried played Buckley. This episode aired on August 10, 1944.