The Mystery

From Author Wars - https://authorwars.com/publications/the-mystery-332376.html

Overview:

Title: The Mystery
Author: Samuel Hopkins Adams, Stewart Edward White
Year: 2003
Publisher: Project Gutenberg
Price: $0.00
Binding: ebook
Type: Novel
Title Reference: The Mystery
Notes:
Cover illustration and design (viewed in HTML format at Gutenberg.org) matches that of all three 1907 editions (viewed at HathiTrust). (Borders of the front cover images --probably the cloth covers onto which matching paper rectangles are pasted-- evidently do not match.)