"William E. Emba"
The Harley Quin stories (this collection, plus two later stories) are amongst the most peculiar mysteries ever written. (They certainly are Dame Agatha's most peculiar. They were also her personal favorites.)
The broad outline is always the same. One Mr. Satterthwaite,
elderly and independently wealthy, finds himself embroiled in an
old mystery or a soon to happen tragedy. Out of nowhere, Mr.
Quin, or some surprise signal from him, pops up, and by the
most innocent and nonleading of questions, Mr. Satterthwaite
finds himself unraveling the mystery. He doesn't actually
solve it, so to speak, but just finds that the relevant facts
are suddenly apparent.
The stories are best read in order (in particular, the collection
does not have a table of contents, no doubt to discourage random
access), as the sense of strangeness grows from story to story.
One finds oneself embroiled in the metamystery of who or what is
this Harley Quin.
In "The Bird With the Broken Wing", Mr. Satterthwaite finds
himself called to house Laidell by Quin via a round of "table
turning" (a forerunner of the Ouija board). By this time in the
stories, Mr. Satterthwaite knows that a call from Quin is always
important, and he leaves for Laidell immediately.
The owner turns out to be "a most brilliant mathematician", who
had authored a book "totally incomprehensible to ninety-nine
hundredths of humanity". And like the impact his professional
work had on ordinary people, so too went his personality. He was
essentially one with the furniture, whom servants and guests
equally had trouble noticing. And then something happens....