Hey GrannyGrump,
Thank you so much for uploading this tale and for the hint regarding the header illustration! Not so sure I would have detected this without your hint, watching this with the ReadEra app on my smartphone. But having turned it into landscape mode for this particular purpose, the eerie details of the illustration can be seen indeed.
One question before I start reading -- is the Author's Preface possibly a spoiler in this case and should one better start with the Prelude?
Finally one little observation:
In the reading list (list of book covers and titles), the title is missing a letter, i.e. the final "w", see the following screenshot
https://www.directupload.net/file/d/...x62cxr_jpg.htm
Thanks again!