Letter to Sydney B. Whipple (9 may 1923)
From The Arthur Conan Doyle Encyclopedia

This letter was written by Arthur Conan Doyle to Sydney B. Whipple (managing editor of the Denver Express) on 9 may 1923 from The Brown Palace Hotel in Denver, Colorado, USA.
The letter was published by Houdini in his book A Magician Among the Spirits (1924).
Letter
The Brown Palace Hotel
Denver, Colo.
May 9, 1923.
Sir:—
The report in the Denver Express that I offered to bring back the spirit of my mother for five thousand dollars, in order to confute Mr. Houdini, is a monstrous fabrication, and I cannot imagine how you dare to print such a thing, which is on the face of it so blasphemous and absurd.
What actually occurred was that your reporter said that my friend Mr. Houdini had wagered $5,000 that he could do anything any medium could do, to which I answered "To do that he would have to show me my mother." This is surely very different.
Yours faithfully,
(Signed) A. Conan Doyle.